Auto body repair & detailing: Old fiberglass and decal removal, camping trailer, scamp

Question
I just purchased a 1976 Scamp camping trailer in Phoenix, Arizona.  The thing is in nice condition but I'd like to spruce up the exterior and that involves removing the baked-on original decals as a first step.  I've experimented with scraping with a blade, which sort of works but is tedious.  Sanding might work but I'm uncertain of if this is a reasonable method and if it is if I should use a rotary or vibrating sander.
 Once the decals are off how would you suggest refreshing the finish on the fiberglass?
 I'd assume that the new decals would go on after the finish is refurbished or replaced.  True?
 Thank you for your time and expertise.

Answer
Unfortunately there is not an easy way to do this. Sometimes a citric based cleaner will soften the decal up enough for removal with a razor.

Sanding will damage the fiberglass and require refinishing.

Also note that after removal their may be a shadow left on the trailer....the decal has provided
protection from normal wear and the best way to cover that back up is with new decals.