Bondo gets a bad name bud. Bondo is sold by auto zone and Walmart. Two places I would never buy materials to refinish a Auto of anykind. There are state-of-the-art compounds in the new Poly fillers out there that when used properly have great results. A body soldering kit is nice but, really overkill for what you are trying to achieve. Get some nice Platinum body filler made by 3M or Norton. It sands very nice with 80 grit paper and can be primed and painted over with just about anything.
Fwiw the soldering kit is just a waste of money. Remember your not building a 150k street rod. Like pictured above.
I guess I was using "Bondo" as general term, and there is a lot of places I will end up using it, but the floor of the bed, right at the back where it will see the most use, isn't really a place I feel comfortable using it. Yeah I plan on using a spray in bedliner, but I'm expecting right there to see a lot of use, and it's one of those places that I can see the floor getting dented, and body filler cracking, then causing issues with the bed liner.
Part of the reason I want to try the body solder is my Dad. This is the first, and possibly only time I'm going to get to work on one of my big projects, let alone something that he can remotely relate to. Lead work is something he never got into, be it because he is his own worst critic and didn't think he would be any good at it, or maybe he never really had the oprtunity, you know with all that "lead poisoning" hoopla a few years back
, or he just liked body filler, I don't know but I think doing the "lead" work with him would be a great experiance, for both of us. Some of his biggest idles created the term "Lead Sled", I want him to see that he is just as good as they are, or at very least, he's raised a son who isn't afraid to dive into the same kind of work that they did. For that, the cost isn't a factor.