As previously suggested, as your RV dealer where they get the Ford warranty work done. Or ask your local Ford dealer for the closest Ford TRUCK dealer. My local Ford dealer recommended that for anything beyond a simple oil change. They don’t have a bay big enough to get a MH into, and the oil changes were canceled if it was raining.
If the warranty item is time or mileage sensitive, at least get it on record, start a work order?
After my warranty ended, I started going to a local independent garage that had bays large enough for every type/size of vehicle.
Ken