Auto body repair & detailing: rust, nissan hardbody pickup, epoxy primer

Question
I have an 89 Nissan Hardbody pickup. I want to prep for paint, but found the bed had some areas that were rusted through.(around the tire wells) I used a grinder and removed the rust. What is the best and fastest way to repair these holes and get them ready for paint.

Answer
Rust is like cancer, you can't get rid of it unless you remove it by cutting it out. If you want permanent fix weld in new metal and body fill to even out and paint. For a 2+ year fix, sandblast, paint with a light coat of epoxy primer and then sandable primer over than then sand and finish.