Wiz,
Ford, GM and FCA all have wobble problems when towing a EPS (Electronic Power Steering) vehicle. EPS does not have adequate damping unlike hydraulic. Hence the fix to leave EPS on when towing.
And that power comes from the battery when towing. And I suspect the power consumption is significant when towing but that is why I asked if there were any actual power measurements.
The OP stated his battery would be dead at the end of a day unless the car was started during the day. Lots of loads including EPS are involved.
I agree that a DC-DC converter might be a solution. I'd want to know the loads and wiring before deciding on a solution.
There is some indication that the EPS/wobble problem is starting to be addressed in some 2019 vehicles.