How big is the hole? I assume it is just a hole for a clip? My only thought would be to use automovie masking tape to put as close as you can to the area you want to repair. (to circle or sqaure the area in) then sand or sandblast the rust away, fill in the hole with body filler. (welding would be better)Spray or brush primer on. Sand it, then brush or spray just a bit of your paint on. The masking tape around the area is so when ya work on the area you won't get sanding scratch marks past the small area you want to work on. It will be less obvious. If the colour is non metallic you can colour sand it and buff it out and no one will be the wiser
If it is a metallic colour you will be left with a circle or square mark around the repair and the paint won't blend right. But if you plan on repainting the whole truck or fenders in the near future i would just touch it up now. Then weld over hole before ya paint the whole panel. Just an idea. Good luck!
