I have the class C RV endorsement which is a misnomer. It's more accurately called "Restriction 41" which specifically addresses 5th wheel trailers over 10K but less than 15K. I had to take a written test which, I believe, is the same one for non-commercial class A. No medical exam, Dr. note, etc. ... just the written test. Also, there was no fee. I would have had to retake the standard class C written test. But, I had recently renewed my license within 90 days - so that was waived. The biggest challenge was finding a person who knew what it was and what test to give me. It took one clerk and a supervisor (and about 20 minutes of searching).
On the front of my license:
Class: CM1
On the back:
Class: Class C & M1-Veh w/GVWR<=26000; No A; 2whl M/C, Mtr-drvn Cycle, Scooter
Endorsements:None
Restrictions: 41-Class A restricted to operating 5th wheel travel trailer between 10,000 and 15,000 lbs GVWR
