rotating on butt?

In my S1-X, fixed foot board, I'm supposed to fit, i.e. 6' 2" tall 34" inseam, knees seem to be at correct height, I don't seem to be able to rotate my butt as It fits tightly against the back of my seat. I demoed a V-12 a week ago I felt that I had a little more room to rotate with the pedals at full extension.
Any similar experiences?

You won't be able to move the hips/butt much if its jammed up against the back of the seat, a little more leg room allows your hips to move back and forward and thus rotate easier.

Great! Can't wait to give it a try in a V-12 which I feel is a little bit less stable than my S1-X. No problem, as I am persistent and patient. The entire surfski/K1 is a personal challenge to me and I'm loving it!