Note: Forgot, mine is a 2005 with 5/16's or 3/8 inch bolts welded in the end of the handrail tubes so it is bolted from the other side of the FRP. Later versions had round plates with holes for self tapping screws which would be a snap to remove.
Thanks John, very considerate. Here's a duh moment. Spoke with Pete at Marlow Hunter and he sent some drawings but proposed that maybe you could get away with only taking off one rail. Wow, don't think so but it's worth trying.
Anyways Hunter uses Whisperwall in the overhead of later boats from about 2002. It is already removed so only one aft bulhead cover type piece to remove and all the fasteners are available.
Another thought is to make the U shaped slider more of an L with a serif at the end of the bottom part of the L. Butter the L with some Dow Corning 758 and it should stay there. Or if need be a few #6 short self tappers truss or flat head.
Charlie