I've thought about these as well, having seen them (or something similar) on either pulpit corner of a friend's Hunter 336.
Zarcor (who made the swiveling drink holders I have on either side of my steering pedestal hoop, and make a very quality product) offers them, albeit not for free.
www.zarcor.com/products/sternperch
They also include a cupholder in each, seat pad, and rail cover to serve as a backrest. But my rationale for this not being a good solution for my situation is listed below:
My chief concern/reason for wanting a humped helm seat is for seated visibility. I don't have an autopilot, and sail in water requiring constant steering attention (both from a windshift standpoint and avoiding commercial vessels). So I'm either standing at the helm or attempting to place an appropriate number of cushions beneath my keister to see over the coach roof. When heeling, the latter no longer works, but I'd think it would with a humped seat keeping 1 seating surface relatively level through most heel angles. I do have a concern with foot placement to allow for good leg circulation (feet dangling for hours at a time would be less than comfortable), but had some ideas for accomplishing that without ruining standing room at the helm.
If anyone with a 35-3 who dislikes their humped helm seat is interested in a trade for a flat one, if be interested (assuming the molds for the perimeter/fit of the seat remained common).
Thanks again to all for their input - I love discussing these problems and hearing all of the creative solutions others have arrived upon.