Paint Experts: Process Advice Needed

Epoxy primer would be my choice. If your garage is relatively humidity free you could probably get by with regular primer but not worth the chance.

There's not much humidity in my neck of the woods, especially this time of year. I just hate the idea of sanding the epoxy-primed panels when I re-seal and paint them down the road. That stuff never sands too well. Is there one that sands easier than most??