I don't think that will work well in this situation. The mounting studs on those lamps are usually at least 1/2". Plus, it's on the top of the fender. Bending it might cause damage to the fender.
I'd go with cutting the nut. Cut it on the side of the flats, paralell with the bolt. You might have to do 2 cuts to get it to come loose. Don't cut too deep if you want to try to salvage the lamps. That'll usually do the trick to get the nuts off.
