The white high build should be good for blocking. If you use the black or dark gray guide coat on it, low spots will stick out like a sore thumb! When I finally get to the point of doing the bottom of my Duster, I think I'm gonna do the SPI epoxy, and then before the recoat without sanding window runs out....I'll turn around and shoot it with Upol Raptor bedliner. I'm still on the fence about doing it that way, or wait until it's in color and clear to do it. It may just be easier to mask off the body, and flip it over and spray the black bedliner material then?