I'm sure your 200' of signgold is not one continuous piece, but smaller pieces cut out from one roll side by side, so your laminate should be able to be cut the same way...
I always cut and weed the vinyl - leaving my registration marks, then laminate the material and cut it again with the 1/4" overhang and the "finished" material is ready for installation in one shot. Applying laminate after the graphic is on the vehicle seems to be adding another step to the install and another place where you could mess up. Getting wavy/stretched is common installing thin laminate or getting bubbles/imperfect laminate adhesion once you're on-site.