I am currently doing body work on a pickup bed. I have pulled out one dent on the lower left rear corner of the bed. The area under the tail light. I really can’t access the area inside of that part of the body. I thought about the hammer and dolly method already. My question is what should I use to fill in the low spots? I want to make sure that whatever I use is going to hold up to it. Any help is immensly appreciated.