I've seen a a lot of cars on rotisseries and had a couple of my own on them. Both were uni-body cars. I've never seen an issue of the bumper mounts not being strong enough, BUT, a stripped car being much lighter is the only way I'd do it. When I had my Mach on one, I used the same holes that the factory used, in the bottom of the rear frame rails, and the front bumper mount holes. If the mounts are made correctly, or at least adjustable, you can keep the center of rotation in an ideal place, which is definitely a good thing.