I have 2 small area s of the drip rail that I have completely cleaned and pre-treated with the POR prep products and then a small amount of POR putty. I will use a quality seam sealer after I spray the epoxy primer.
Fred, 1. do I need to get 100% of factory paint/primer off before using the epoxy. 2.I have read that you scuff the epoxy with 180 prior to any 2k surfacer. True? How do I do body work after DTM epoxy if I don't remove it.
Bondo is good on bear metal and will last no problem just don't use cheep bondo Evercoat is a good bondo and about $80 a gallon but trust me on this don't buy cheep bondo you will work hard sanding it and spend more money on sand paper.
Getting off all the old paint would be good but the primer no the little you leave behind is not a big deal even paint as long as it has a good bite to the metal. I use 80 grit sand paper under the bondo but if over 1/4" I use 36 grit. bondo the bad spots block then prime. Best to get the bondo work done as good as you can before primer.
2K is a big *** filler kinda like bondo that you spray on I think, never used it.
epoxy primer is made to etch bare metal and be some what of a filler and you bet 180 grit before you put down the 2k.