You ride a recumbent exercise bike comfortably, why not consider a recumbent bike? They come in 3 wheels, and 2 wheels. They all have back support, and can cruise at a decent speed and distance. They run from 20 lb speedsters to heavier and slower ones. They also can have a neck rest, and put no pressure on wrists, shoulders and neck. The seats are way more comfortable, and have full back support.
If you'd rather have a bike than a trike, there are all kinds of different configurations for 2 wheelers, for racing, touring, comfort riding, riding with upright bikes, whatever you want.
Bob