Bumper guard removal on a 73 Scamp?

Hello all,

I used the search button but only found one thread referencing the proper way to remove the hideous bumper guards off of my 73 Scamp.

I busted a few knuckles trying to get them off, but to no avail. First, I sprayed them down with some PB Blaster and let them sit. I grabbed my socket wrench and tugged on them for a while. I believe the bolt size is different between the front and rear bumpers.

Anyways, using the socket wrench, the bolts just spin. I can't see anywhere to get the rubber pieces off so that I can grip the other side with a wrench.

Am I missing something? I don't have any type of grinder to cut the bolts, so I'm hoping that I am just missing something. It's darn tough to get in there and do anything. Thanks for any help!