Hi There,
We took out the back of the seat in the 35s. It does not look very pretty but it gives you at least 10 cm more space for forward movement. As we fly worldwide with our planes, the bum factor is quite importat and every couple of hours i go to the back relax or do some exercises.
I use also a towel when it's hot outside and put it folded around the touchdown zone of the bum. It works for me.