Are you using the Jeep wiring harness that has a plug from your coach and then runs under the hood to the factory connector? This runs your lights and SHOULD charge the jeep provided your coach is putting out the correct voltages on the right pins.
I tow my JK behind the motor home and use the "Toad Charger" system it was easy to install and has worked well for 3 years and about 8,000 miles. I also use the "Cool Tech" wiring harness for the lights.
My supplemental brake system specifies using a charge line from the towing vehicle. To accomplish it, a switched, fused 12 volt line from the towing vehicle is wired through a 20a circuit breaker to the Jeeps battery. Works great and should solve your discharge problem.
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