Investigating DL requirements in SC for RVs was and still is quite frustrating.
When we transitioned from a gasser to our current DP and asked the sales person at the various dealerships we visited as well as current owners that were selling their rigs they
all told us "no special license needed".
When confronted with a printed page from the SCDMV website at least the sales people fessed up but with the caveat that the regs were never enforced.
Turns out the regs appear to be never enforced. Indeed no one at the test centers or DMV headquarters could ever tell me exactly what was needed.
In fact at DMV headquarters the CDL people told me I needed a regular DL and the regular DL people told me I needed a CDL.
In the end if you go to a test center and tell them you need a class E or F test they punch a button and the proper test comes up on the test computer.
If you schedule the driving test a CDL tester shows up and has a card for class E or F tests and that is the test they administer . They all, however, remain clueless as to the need and overall requirements for the license.
Indeed the website is unclear as to whether or not the safety driver must have the proper license or just a regular license.
I have since talked to many State Troopers, deputies, and local police and they all were not aware of a need for a special license for over 26K or over 26K and towing.
The next issue that always comes up:
"But if you have an accident without the proper license your insurance will not cover you."
Here my experience is limited to conversations with 6 individuals who had accidents and did not have the proper license.
Not one of them was cited for not having the proper license and not one was asked by their insurer to see a copy of their license and no ones claim was denied by their insurance company. YMMV