The 36-man contingent, who will play two Tests in England and one each against Ireland and Wales in November and December, will be named on Monday.
But the tour comes at the end of an arduous season for them and Mayhew said: "There is concern because some players are worse off than others.
"It is getting to the stage where we've had players who have been relieved to be injured just so they can get a break. Not that they want to be injured, but mentally they just need to get away for a while."
Mayhew said Auckland, who contributed 11 players to the All Blacks for their eight Tests from June to September, are one of the worst affected sides in the National Provincial Championships because of the intensity and length of the season.
"They went through the Super 12, played and won the Super 12 final then had a lot of players in the All Blacks, and now they're having to play in a tough NPC competition," he said.
Mayhew said the All Blacks coach, John Hart, is aware of the strain on his leading players and is doing all he can to ensure the tourists will be refreshed by the time they arrive in Britain. Mayhew is relieved the Test squad will not be put in such a stressful position again, leading into the 1999 World Cup.
"Next year I think we only have seven Tests and no end-of-year tour, and that will make it more bearable for the players," he said.
Australia's provincial rugby union players have been guaranteed minimum salaries of pounds 25,000 under a historic agreement with officials.
More than 100 players from the three provincial sides and a selected squad of elite national team players will benefit following the conclusion of year-long negotiations.
Also included in the agreement is a clause which guarantees full payment of player's annual contracts regardless of injury.
The Players' Association president, Tony Dempsey, said the deal, the first of its kind in rugby union, was based on an agreement used in American football.
"It's been a long hard road for us. It's the culmination of 12 months hard work and I'd reckon 50 or 60 meetings with the Unions to get this far," Dempsey said.
"We didn't get all the things our own way but we got all the things we wanted through. There is no other agreement like this in the rugby world."