If the problem is getting a solvent under the vinyl, try a wallpaper bug. It looks like a computer mouse, and has a couple of star wheels on the underside that prick the wallpaper (or vinyl) and leave dozens of tiny holes to let the solvent penetrate the vinyl.
(That was pretty good, I was able to use "prick" and "penetrate" !)
2002 Ducati ST4s - Grey Mouser
1965 Honda Super 90 - project
2002 Ducati Monster - Duc l'orange - sold
1985 Honda XL600R - sold