Meanwhile, England have recruited Bath attack coach Lee Blackett and Sale defence coach Byron McGuigan to join the team’s summer tour of Argentina and the United States.
Blackett, who recently coached England’s A team, fills in for Richard Wigglesworth who has been seconded to the British and Irish Lions for their own tour of Australia.
Sale have produced several notable defensive displays since McGuigan was promoted to defence coach in November, notably beating Bristol 38-0 at Ashton Gate and keeping Saracens to only a score in a 25-7 win on Saturday.
“Lee and Byron both have a mindset and approach to their coaching that very much align with how we want to continue to play,” said head coach Steve Borthwick.
England play Argentina on 5 and 12 July before a one-off Test against the United States in Washington on 19 July.
However, Sweeney, who survived a vote of no confidence by RFU rebels last month, said the game’s finances were unlikely to be bolstered by renting Allianz Stadium to Premier League club Chelsea.
The football club are exploring the possibility of expanding their Stamford Bridge home, six and a half miles from Twickenham, or moving entirely.
An arrangement would suit the RFU which posted record losses in its latest accounts and is planning a redevelopment of its own.
However, the concerns of local residents and Richmond Council, who Sweeney is attempting to persuade to allow more events at the 82,000-capacity venue, are likely to be a formidable obstacle.
“There have been conversations previously about Premier League clubs coming here,” said Sweeney.
“It would be a big financial number, but I know Richmond borough would definitely have a conversation about that.
“I just think, in terms of impact on local residents, numbers of fans and so on, they’d be a little bit more sensitive. It may depend on which club it is.”