Removing Lower Valance

Okay so apparently my Barracuda has been hit on the passenger front side at some point in the past. Well rather then fixing it they hid it and now that I am trying to replace my lower valance I am finding how far the damage goes. Turns out the person who "fixed" it used a bolt and nut to attach several of the mounting points. On top of that the bolts/nuts seems as though they were used and rounded. I can not get any power tools in there I have tried a metric wrench slightly smaller and it won't grip the head. I have tried heat and that allowed me to snap the head off of one. Any ideas one the other 2? Options for breaking them or griping or anything?

can you get a long bolt in there and tack it to the bolt head with a mig. Works like a charm.