I am just about finished with the undercoating then up on horses for the final body work inside and out. The hardest part of undercoating is the prep work. It's gotta be clean. As mentioned earlier, I pressure washed first, then did some sand blasting, washed down with the purple stuff (degreaser) from Wal mart, and sprayed on the good stuff.
Here is a delay that came into play. When I removed the body from the chassis, all nine bolts on the pasenger side came out smoothly. On the drivers side all came out OK except the last bolt, and it broke off. Murf's Law! "Anything that can go wrong will go wrong". Since I had the body laid over, it was a good time to tackle removing the bolt. I spent a half day removing this 8 MM bolt. At first I thought about just leaving it, but it would have haunted me leaving it in. What frustrated me was, I drilled the smallest hole all the way through the center of bolt, (lucky there) and continued to use larger drill bits until I got my easy out in place. No luck even using heat. Finally I decided to and use the closest drill bit to the bolt size and drill through. If I ruined the threads so be it. The inserts don't have enough meat to drill out and re-tap. Was I lucky my efforts were a success. The last of the threads came right out, and the insert threads were untouched. I thought it would be a good idea to chase all the inserts, including the fender inserts. I had no luck checking with NAPA, Autozone, and Advanced Auto for a tap. I finally found a 8 x 125 tap in town at a Fastner Company.
All my bolts now go in just using my fingers.
I started removing the headliner clips on the door post and those above the door. Using some pliers I bent the tabs on the door post back and forth till they broke off clean. My flap disc removed the small edges that were left. On the top I was able to remove the strip by using a piece of wood I cut at a angle and placing it next to the clip and pulling against the wood with my channel locks snapping the strip from the spot welds. The strip came off nice and clean. 
I am not looking forward to August!