For fast dealer rust work I wouldn't bother using epoxy I would sand blast (if I had too) and fill pitted areas with putty and prime with 2k sand and paint (spot if you can). Time is important and rust work for dealers is so they can sell fast and more then likely don't care they just need it to look better then it does now.
I've tried everything to get them to last more than a few weeks. I use copious amounts of kitty hair, 2k primer, sandblasting..... but a couple weeks out and it creeps back. Been told use panel adhesive but that takes too long to dry. Epoxy sealer is ready fairly fast. It's worth a try. I may have to go to JB WELD.
Sometimes you have to think like them, you want cheep and fast?... Well here you are. If they want better they can pay for better and give you a little extra time to get it done, other wise I say too bad you get what you pay for in the time aloted.
I feel for you AAE, this is the type of work that just sucks away your soul and any enthusiasm you might still have. That being said, DATEC is right,cave and pave is really the only way to eek out any profit on jobs like that.
AAE, just mix epoxy 1:1:1 with reducer. Spray 1 light coat over area after blowing off dust and wiping down with 700 w&g remover. Wait about 20 mins or so then proceed with filler. If below 75 degrees use heat gun or lamp to kick it for 5 mins. I have used this for fast cheap repairs and it works well. I would only recommend this for no-warranty lot work.
Did a repair on my sons car this way. Had it for three years before selling and repair was still rust free.
Kent, I would think with that shortwave you have try this.(dealer work only) Don't reduce the epoxy, spay one wet coat and 10 mins with that lamp at 110-120 when cools slap the filler on.