Front bumper cover bolts to fender spinning inside bumper cover

Anyone ever had this problem. They are made into the bumper cover so there is no way to hold the other end of the bolt. I've got a dremel tool and the only ideas I have is to cut a flathead slot on the end of the bolt so I can hold it with a screwdriver or holding it with vise grips, backing nut off as far as possible, and cutting bolt if needed? Any other ideas. Bumper cover is slightly busted and cracked near fog light opening, so if I mess it up, it wont be the end of the world. I have a replacement cover I can take off my 91 roller.

Thanks Riceslayer. I havent really thought about pulling everything off together. I'm in the process of moving inner fenders from wrecked car onto my good car. I'm also gonna install radio antenna cable while fenders are off. And also moving fog light brace from wrecked to good car because previous owner removed it.