Skimmed through and watched a couple minutes of the video. Nice to see a crew cab frame, as it is only recently I learned not all 2nd generation S10 frames were flimsy. I have only owned RWD regular cab S-trucks. After carefully considering options, I used Purple Power and a gas pressure washer to prep the inside of a MI S-truck frame I did couple years ago. Given the amount of factory, waxy undercoating that still remained and difficulty in removing it; I decided to recoat the interior with copious amounts of Fluid Film. I painted the exterior of the frame after rust removal/treatment. With your frame bare, why not abrasive blast the exterior surfaces?