That would probably work fine. Mounting it below deck will affect performance, no matter what your boat is constructed of. It may be suitable for you though and could make installation much easier. You don't want it where you'll be sitting on top of it or right up next to it. It may still work at times, but your body could shade 1/2 the sky if you're close enough. Try it out in a few locations and go with what works for you.I have the h23 that does not have a stern rail would you just mount it on the transom