Thanks for the tips.
It turns out that my favorite home-improvement tool, the sawzall, was able to make short work of the bolts.
I had to cut them at the fat metal bushing that the mounting bolt goes through, it was a lot of material to cut through, but it worked.
If anyone else every tries this method, I would advise taking your tires off first, the tip of the saw can jump and easily cut the sidewalls.
Pete