I've been trying to keep up with all the experts on this tread but to be honest, I am some what bemused at what should not be a problem.
In Oz cat A has a very straight forward requirement. Before CDP you must have the ability to land back. After CDP you must have the ability to fly away. It does not matter if you are on a rig platform 200 ft above sea level, on a work boat 15 ft above sea level, on a mountian pad, in a jungle clearing or a 10000ft runway. You simply adjust your take off weight to suit the cat A requirement; this of course means that you will have different take off weights to suit the differing conditions.
All twins flown at the correct weight must be able to maintain level in the cruise on one engine at specified heights. So if you take off at sea level to fly over mountains, you must use a weight that is suitable.
After CDP from a helipad, you must reach VTOSS and started climbing by 35 ft, no reject area is required. If you can't do that, you are too heavy.
So I just don't see the problem. Fly at the correct weight and your company should pass those weights on to the customer if necessary.
In OZ we rarely use cat A unless the customer requires it.
