Insurance and law are separate things. If you pull out an insurance policy on your motorhome it will cover you whether you have the proper license of not. However, this does not mean you will not get in trouble with the law.
Auto insurance is necessary whether you have a license or not. This is because the policy protects the vehicles and its occupants. Auto insurance is not related to a DL, however. A DL is a state-mandated requirement to operate a vehicle. If you are caught without one you get fined and even apprehended. Your auto-insurance will still cover any damage done to the vehicle. The same can be said of your motorhome. Your insurance policy is not affected by state-mandates as it covers the RV itself and its occupants. If you have RV insurance than it also covers the assets inside as well. Your DL is required to operate the vehicle and has no bearing on the coverage attached to it.
As stated before this does not mean you will not get in trouble. South Carolina requires a Class F and if you do not have it they will fine or apprehend you. Rest assured that in any case the damage to you motorhome will be taken car of.