Help remove welded nut bracket from back rail

I was installing my new trailer hitch and all the bolts from the welded nut bracket inside the passager side frame rail broke off. Now I need to remove it. The only way I can see doing this is buy removing the rear bumper and then pull it out. Is there any other way since remove the rear bumper is quite a job compare to installing the hitch. Possibly pulling it out inch buy inch and cut it with a bolt cutter as I go along?

Any advises?

I finally got the bumper off. It was not that bad. The problem now is that I have the bolts for the hitch but I will be missing one and the square slug for the heat sheld and muffler bracket. I will try to drill out the broken bolts in the nut braket to reuse it but I don't think it will work.

You might be able to get a nut strip from the dealer.

Fred