If you're breaking studs off, you're using too much torque. The plastic nuts are only supposed to be torqued to about 10-15 inch-pounds, which is just barely snug when tightend by hand.
I had a stud pull out on my old car. I fixed it by welding the stud to a fender washer, and then JB Weld'ing the stud/washer to the original location. Just make sure that you remove all the undercoating and paint on the body, so that the metal surfaces are bare and clean. Also, you may need to user a hammer to flatten the area where the stud came out, since there will probably be a raised lip. Then, once the glue has hardened (get the normal JB Weld, which takes 24 hours, not the 5-min stuff), paint over the area with a good rust-proofing paint.
Done properly, a repair like this should last the life of the car. Mine was still going strong nearly two years later when I traded it in.