I emailed Bobbie Mayer (author of the book I suggested in an earlier post)...
here is the short version of her answer. "I" here is her talking, btw.
1. I doubt they would want the dog in the cart in the trailer, anyway, so they'd most likely take him out and carry him into the trailer.
2. The issue with the ramp is more the width than the incline, especially for a dog the size of a GSD.
3. In her opinion, the best option would be to have the dog in a cart when outside, and use a harness to assist the dog up the ramp.
4. The Ruffwear Doubleback harness is really supportive and can be worn in a cart, so they might consider that and then take him out of the cart to go up into the RV
Samantha (the poster)
Tim, DH and driver of the CorgiMobile
Dexter and Dora - Pembroke Welsh Corgis
Gone but never forgotten -
Beth 1/11/94-6/3/09
Pippin 3/16/05-11/4/15
Buddy 11/7/05-10/24/16
Diva 1/9/09 - 8/20/20