Another thing you can look at is where the seat back is located. There are two different anchor holes in the body where the seat back screws down, about an inch or so apart. Mine was in the forward position and I moved it back. Not for knee room but because I made a bigger/thicker backrest. You'll probably need better foam in the seat if you move the backrest, if your butt is hitting the plastic ridge behind the seat. Maybe I should start selling foam and backrests.
To Invent, you need a good imagination and a pile of junk. (Thomas Edison)