The Australian-English phrase to cover more ground than Burke and Wills means to travel a long distance.

This phrase refers to the Burke and Wills expedition of 1860-61, organised by the Royal Society of Victoria. It consisted of nineteen men, led by the Irish soldier and police officer Robert O’Hara Burke (1821-1861) and by the English surveyor William John Wills (1834-1861). The objective was to cross Australia from Melbourne, in the south, to the Gulf of Carpentaria, in the north. At that time, most of Australia’s inland was largely unknown to the European settlers.
Seven men died in the attempt, including Burke and Wills. Only one of the four men who reached the north coast, the Irish soldier John King (1838-1872), survived to return to Melbourne.

Arrival of Burke, Wills and King at the deserted camp at Cooper’s Creek, Sunday evening, 21^st  April 1861 (1907), by the Australian painter John Longstaff (1861-1941)—image: National Gallery of Victoria:

 

These are the earliest occurrences of the phrase to cover more ground than Burke and Wills that I have found, in chronological order:

1-: The first two are from advertisements published in The Age (Melbourne, Victoria):

1.1-: Of Saturday 19^th January 1952:

SUNNY QUEENSLAND! GREEN right thro’ recent Dry Spell. 200 acs., renowned MALENY ¹, ½ hour Surf, good home, 80 Dairy Cattle, Pigs, lovely perm. CREEKS, fully equipped. Returns £1500 yr. the easy way off the Pastures Clover, Kikuyu. And there’s SCOPE for INCREASE. You’ll cover more ground than Burke and Wills to find better value at £6600. C. D. EDWARDS, Union Bk. Chs., Brisbane. (Same Address 24 Yrs.)

1.2-: Of Saturday 16^th February 1952:

SUNNY QUEENSLAND. This farm was green right through recent dry spell. 200 acres, renowned MALENY ¹, 70 miles B’BANE. Good home, 80 dairy cattle, pigs, lovely perm. CREEKS, fully equipped. Returns £1500 yr. the easy way off the pastures clover, Kikuyu. And there’s SCOPE for INCREASE. You’ll cover more ground than Burke and Wills to find better value at £6600. C. D. EDWARDS, UNION BK. CHS., Brisbane. (SAME ADDRESS 24 YRS.)

¹ Maleny is located in South East Queensland, near the Coral Sea coastline.

2-: From the account of a horse race, published in The Mirror (Perth, Western Australia) of Saturday 21^st February 1953:

Early Impressions Put Four Pacers In Class Of Their Own

On Wednesday’s mile and a half heats four pacers emerged with outstanding prospects for the final of the Interdominion Trotting Championships to be held at Gloucester Park Saturday. They are Blue Mist, Beau Don, Ribands and Recovered […].
[…]
Ribands put up an extraordinary display and he too is a super horse.
Without a doubt if the handicapper had seen that race before deciding on his task he’d have handicapped Ribands 24 yards behind Avian Derby.
Ribands galloped off the mark, covered more ground than Burke and Wills, and was being held together at the finish as he repulsed the efforts of Avian Derby and Recovered.

3-: From The best race callers in the world, by Lenore Nicklin, published in The Sydney Morning Herald (Sydney, New South Wales) of Saturday 29^th October 1977:

Some race callers are stylists, some speedsters and some comedians. Bert Bryant ²,  retired this year, was the arch-comedian. Horses would hang on like granny’s tooth, be as weak as the skin on Mother Hubbard’s custard, cover more ground than Burke and Wills, or be looking at more tails than Hoffman ³. The field would be spread out like a jar of Vegemite, stragglers would be late for school. “You’ll have to go out looking for them with a hurricane lantern,” Bert would say.

² Ernest Bert Bryant (1927-1991) was an Australian race caller.
³ This is a punning allusion to The Tales of Hoffmann (French: Les Contes d’Hoffmann – premiered in 1881), an opera by the German-born French composer Jacques Offenbach (1819-1880).

4-: From the column Backstage of Racing, by Bert Lillye, published in The Sun-Herald (Sydney, New South Wales) of Sunday 16^th September 1979:

Cecil Hopkins, who turned 85 last April, […] assisted his older brothers, Tom and Charlie, in the compilation of form guides which flaunted the laws of libel with observations that no one would dare print today.
It was commonplace for one of the brothers to write that a horse had been “strangled”, “choked”, “thrown at the start”; or had covered more ground than Burke and Wills.

5-: From the account by Mungo MacCallum of “the inaugural Super Rules match between the Reps and the Senate at Canberra’s Phillip Oval”, published in The Age (Melbourne, Victoria) of Saturday 21^st August 1982:

The first few minutes were marked by a surprising display of Senate grey power from John Martyr (Lib, WA) and John Siddons (Dem, Vic) and after about five minutes Don Chipp, who was covering more ground than Burke and Wills and looked as if he might end up in a similar condition, received a dubious free kick and goaled.

6-: From the Sunday Independent (Perth, Western Australia) of Sunday 18^th November 1984—as quoted in A Dictionary of Australian Colloquialisms (Sydney University Press in association with Oxford University Press Australia, 1990), by Gerald Alfred Wilkes (1927-2020):

‘He’s covered more ground than Burke and Wills’ is the stock condemnation of a racehorse wandering all over the track.

7-: From an article about the race callers, by David Hickie, published in The Sydney Morning Herald (Sydney, New South Wales) of Monday 4^th February 1985:

Bert Bryant became king of the extravagant image. Horses would “hang on like granny’s tooth”, be “as weak as the skin on Mother Hubbard’s custard”, “cover more ground than Burke and Wills”, or “be looking at more tails than Hoffman”. The field would be “spread out like a jar of Vegemite”, stragglers would be so far behind the field, they’d be “late for school”, or “you’ll have to go out looking for them with a hurricane lantern”.

8-: From the account of a horse race, published in The Age (Melbourne, Victoria) of Monday 21^st July 1986:

Rapid Elk, who usually does his best when allowed to drop out in the early stages of a race, was forced to race wide and close to the lead. As racing scribes would say, the colt was covering more ground than Burke and Wills.

An Americanised form of the phrase occurs in Wrona gets the call at Santa Anita, by John Cherwa, published in the Los Angeles Times (Los Angeles, California) of Friday 25^th March 2016:

Michael Wrona, who left Australia 25 years ago to pursue his dream as a race caller, was named the announcer at Santa Anita Park, replacing the popular Trevor Denman […].
[…]
When Wrona came to the U.S. in 1990, legendary Australian announcer Johnny Tepp [misprint for ‘Tapp’ ⁴] suggested he retool an old Aussie race call.
“When a horse is covering a lot of ground, trapped wide around both turns, there’s an expression that a horse is covering more ground than Burke and Wills,” Wrona explained, referring [to] two famous Australian explorers.
Tepp thought if you replaced Burke and Wills with Lewis and Clark ⁵ it might work.
“So I did and it got a great reaction,” Wrona said. “Every now and then I’ll throw in ‘covering more ground than Lewis and Clark,’ if some poor horse is posted five wide around both turns.”

⁴ John Tapp (born 1941) is a former Australian race caller.
⁵ The Lewis and Clark Expedition (1804-06) was a U.S. military expedition across the Louisiana Purchase to the Pacific Ocean, led by Captain Meriwether Lewis (1774-1809) and Lieutenant William Clark (1770-1838).