Great suggestions, thanks to all.
The 3M wheel was new to me so I searched it and found a YouTube video where a couple used 4 of them over something like six 8 hour days (Yikes!)to remove the decals from their RV.
I decided to at least try the heat gun first, mindful of the warning about panel delam. The 1400 Watt heat gun on the low setting worked well. The panels never got above 140 - 160F (which I figured is no hotter than the panels get in sun in AZ).
The decals pulled off after heating with a broad tip held 1/4" off the surface. Holding the gun so that the hot air blew away from the area being pulled off enable me to slowly pull entire labels off in one long motion (after a little practice).
My decals were only 7 years old, so others types or ages might be much harder to remove.
Interestingly only the blue decals looked bad and started peeling on the edges. Perhaps the tan decals didn't get as hot.
Thanks again - this info should be of use to many forum members.
If I buy another RV, it will have full body paint not decals if stored outside!