As you probably know, your Dutchman camper battery is only for powering your camper's interior 12-VDC systems and appliances, and should not be wired to your camper's running lights.
Being this old, You should check the following potential problems;
1- The GROUND wire for your battery and the GROUND wire from your tow connector should both be firmly connected to your camper's chassis, and the connections should not be rusty or loose.
2- the HOT wire for your running lights of your camper should be wired to the connections shown on a standard wiring chart for the specific type of connector you are using (4-wire, 5-wire, or 6-wire). Check this article for the proper connector wiring;https://axleaddict.com/rvs/RV-Towing-and-Electrica...