Rusted on rear bumper cover bolt Options

[6thcelestial]

I recently decided to replace the rear bumper reinforcement bar on my 95 gt hatchback. I have gotten all bolts and screws either loosened or removed except for the one bolt that is directly above the muffler tip. Due to condensation and heat from the exhaust over the years, it is basically corroded down to hardly anything as is the washer. I cannot just dremel the head off as there is not enough left to do that without cutting into the plastic of the bumper. I was thinking of just taking the bumper off with the reinforcement bar still attached, flipping it over on a table, and drilling into the bolt several times until there is hardly any metal left, and sneak the plastic lip over whatever is remaining. Any other thoughts or ideas? Thanks