So I'm going to be honest, I really don't like polyester resin based products like Bondo. I know that there are projects where Bondo is the right tool for the job, but when I can I try and use something a bit less toxic. I have experimented with quite a few different products, and I shot a video showing off the ones that worked the best for me. Let me know if you have any questions!
Personally I am a big fan of using high fill primers instead of having to do a large amount of paste based mixing. In part cause it also prevents paste bubbles and voids, and if you have good gun control you can limit your waste and additional sanding time quite abit. Though I am sure most of these are still as toxic. So it doesn't really solve that problem.
I also love the high fill primers! I'm using the rattle can stuff though. But ya, still really toxic. When I was living in apartments it was always pain to use the really stinky stuff. Neighbors didn't appreciate me out on my patio looking like I belong on the set of Breaking Bad.