Changing the angle of the seat helped a lot-- I stopped sliding off of it. (Shush, peanut gallery.) It's uncomfortable with the gel seat in place, but better with it off. Go figure. Some days the plain seat is fine, others it starts getting painful and annoying after ten or fifteen minutes. I do at least 30 minutes of riding while I play a set of sit & gos, then often stop to focus on the endgame of whatever tables are still going.
I used my rope bondage skills to mount the gamepad on the handlebar of the bike. Having my hands free has made a huge difference, since I can shift my weight around, rest on the bars, etc. I still need to find some way to raise the keyboard, but it's usable the way it is-- I register for four tournaments and then put the keyboard down and start riding.
I'm currently doing a minimum of one set nearly every day, and sometimes a second set. That's a minimum of half an hour, and sometimes an hour. I find myself looking forward to it, which is well and truly frightening-- exercise has always been something to be endured.
It seems to be making a difference. Plus, I'm making money.