Yes, the proper way to do this as a temporary measure is NOT to use a jumper cable, as both ends are hot and supplied by a large battery bank, and if one end jumped off and touched any metal on the coach, you are looking at an instant WELDING MACHINE and likely fire.
The proper way is to mark and remove a wire from one large lug and add it to the other large lug. Return to original position to disconnect. If you are going to be on shore power the whole weekend (when not on the road) no issue with leaving them in the "both on one lug" position-- your charger will automatically charge both banks.
