I just removed the extra padding from the upright part of my drivers seat. This is a very easy mod (didn't even have to remove the seat from the car) and completely reversible as the foam comes out in 1 large piece. Clip 3 hog-rings to get under the seat cover, and clip 6 more to free the foam.
The side bolsters actually serve a purpose now and give me some side-to-side support, not to mention a little more leg room to boot! Before I felt like I was just resting on top of the bolsters and not in between them.
I did add a small piece of rolled plastic insulation in the lower part of the backrest for some lumbar support. I think it's going to work out very well!