John,
If you want to use any filler first try to straighten the metal to avoid thick applications of filler. I have done many boat fiberglass repairs. I would use epoxy sanding resin & powdered fiberglass cloth to mix a putty type mix & apply. Use acetone to clean tools. Another thought with all the new cars with aluminum body panels there must be new products to use now for aluminum apps. Like others have stated epoxy type fillers would work too. Just straighten the metal as much as possable first & keep the filler thin to avoid cracking out. Be careful with fiberglass resin mixing the hardener, too much & the resin WILL catch on fire. I know from experience & air tempature changes mix ratio. Ive cut boats in half & reglassed for repairs, Look on line fir Filler products possably. Photos of your repairs would help & wear a MASK!! Your lungs were made for O-2 not filler dust please!
