71 Dart Fender extension bolt holes stripped

Good lord... removing the old studs from the fender is a PITA. I had to clamp some Vise-Grips on the part of the stud sticking out the front of the fender, and use a 1/2" deep socket on the inside of the fender to try to loosen the stud from the inside... I managed to put a chip in my brand new paint with the Vise-Grips in the process of removing these stupid things.. One of them, I had to cut off with a die-grinder from the outside... I only got one fender done tonight... I'll do the other one tomorrow, and try not to damage my brand new paint this time :( Are there any tips for removing those studs from the fenders?