For Golden's I have hiked a few times, taken a helicopter, and this year have a 5 day horse pack trip setup for July. Personally, I think the mode of transport is irrelevant as long as a high level of environmental stewardship is maintained. As witnessed last year at Barnaby there are just as many douche bag slobs with physical ability as there are without.
Iasgair, you said you are limited to 1 day but I would urge you to reconsider and at least plan for one overnight. I don't believe that Ice Field Helicopters charges extra for that. If you fly in for just a day you will miss the two best times for fishing; dawn and dusk. Michel lake is a featureless lake that has one shallow flat that the fish move up on only at those times. Otherwise, long line nymph under an indicator and wait.