You need either a switching mechanism (Switch and/or relays) or diodes to keep the power in your RV separate from power in your towed. Most use diodes and you can purchase ready made harnesses for that. I just use a three pole double throw 20 amp toggle switch. Another way some people who tow Wranglers do it, is to install another lamp holder in each tail light housing that is only wired to the plug for the RV.I flat tow my Jeep. What would happen if I used a male/female adapter to attach the Jeeps trailer wire to the tow vehicle? Hooking the towed vehicles output to the towing vehicles output only the jeep would be off. Its a 4 wire one. Don't want to hijack a thread but it seems relevant if it would work.