I have seen spray-on bed liner applied really smoothly. My dad's Dodge has a spray-on Rhino liner, and it is very easy to slide a load on. Are you sure about trouble with slideing your load? However, I'll recomend that you don't put a paint on liner on the bed, but perhaps on the bottom of the drop in liner, it probbably wouldn't ruin the finish at all, and you could competly remove the liner if you wanted to do so.

Logan