There's actually a real art to clearcoating over vinyl. You first need to spray a fine "sealer coat" of clear over the vinyl to help prevent the solvents from interacting with the vinyl. A painter that is familiar with, and good at, this technique is a real find. There's a local shop that handled the graphics of my motorcycle restoration and they're worth their weight in gold.
One solid sheet of vinyl probably IS more forgiving than fine little, pointy, curly q's of graphics though.