The seat is bolted to part that doesn't come off the floor, not to the floor itself. You should find some 5/16 bolts at either end of the adjusters. Be careful as the bolt part is welded on and will snap right off. I've always taken out the framework, never tried to remove the tank though it. I would think that unless you have small hands, you couldnt get the nuts off the tank straps any other way.
