Getting ready to FINISH what was started 9 months ago- finishing touches on MudNurI while talking with Jim (hotstuff) last weekend- we were discussing the cancer his truck has after only 4 years- we started talking about POR 15- and I think i am going to use it, before putting the carpet and interior back together- here are my questions- for those of you that have done the entire floor- how much did you use of each product. did you use the complete system- Marine Clean, then Metal Ready, then the POR 15-- according the the website, the POR 15 quart covers 96 square feet- being completely MATH DUMB- do I need a gallon of the stuff? Do I need to prime/paint OVER this stuff? since carpeting and the side panels- will be covering it, IM really NOT concerned with UA Rays.--- If I only do the inside the the rig- all the floors, and the "walls"... is it still going to keep rust away- or do I have to do the underside too? Thanks guys!!! Brandy LOVING the new Duramax!!!