Chris,
With all due respect, those two suggestions are something we specifically avoid recommending. Generally speaking, those two suggestions are band-aids that don't address the problem(s).
More often then not, assuming a diver can touch his second vertebrate while in street clothes, then the issue isn't one of the ability to reach the valves, it's an issue of technique. Loosening harnesses and/or lifting up the bottoms of the tank presumes that a diver will have two hands free at the time it's needed. We teach and practice that to do this while maintaining prone position, nuetral bouyancy and maintaining good trim and provide for the possibility that a diver may only have one hand available..
Once you conclude that a diver can reach his valves [ ie; he can reach the 2nd vertebrate] before he gets in the water, then if he is having difficulty while in the water you use a process of elimination to determine the cause.
You start with drysuit undergarment, and determine if that is too restrictive. If the diver still can reach the valves then you go to the drysuit to see if that is causing a restriction. If the diver can still reach the valves with drysuit and undergarment then you look to the fitting of the harness.. More often then not any combination of the three are the cause of the restriction. Therefore, it's better to address the root cause of the problem rather then apply ad hoc solutions like loosening harnesses or lifting up the rear end of the tank(s). Also, as Ben mentioned many divers don't go straight back with their arms, and lastly what I notice often is that many divers tend to chase their valves by going vertical. The law of gravity will actually make your tanks harder to reach when a diver goes vertical, but I see it all the time..
I'm not trying to flame you, but since this is a DIR forum I want to make sure the original poster understands our approach..
Regards
Michael Kane
