Joel,

I don't know the Sea Rider at all, but if you try to fit your feet, think about putting a minimal height floor for your feet as well as the raised #3 and #4 frames.
I use 1/8" ply for my foot rest, but it is on top of the stringers. If you made a shelf on the side of the 3/4" stringers at 3/8" height and offset the frames 3/8" lower you would have support for the ply floor. Every little bit helps.
Another idea I read was to double the skin in the area of the footwell to get at least 3/4" extra height. This would probably still cause heel bumps in the bottom of the boat - but do you really care? If you did this you could just wrap a piece of skin over the #3 and #4 frames at the bottom and the 1st two stringers, gluing it on with epoxy (it sticks well) then heat shrink so the full skin lays over it easily.

I also like Nicks adjustable foot rest because it makes it easy to put your feet in with your toes angled outboard, giving some more length if your heels are along the keel stringer.

Have fun, most anything can be done with a little study.

Marc