Easiest solution is magnetic lights, attach and plug into MH. Next is to mount plug on car front and run 4 wires to the back installing extra bulbs for the lights. Plus the wire and plugs from MH to car. Or use the existing car lights installing diodes in the taillights to isolate the MH power and car power. You may also need a small isolator in the MH convert from separate brake and turn lights to the common brake/turn car light. Diagrams and kits are available online.
Why do you want a charge line? It's not needed for dolly towing.
For a charge line use a 6 connector cable MH to car with larger ground and charge line wires. ie For charging. 3 wires for the lights plus the ground. Ground and charge line for the battery with fuse. This leaves a spare wire.
For my non dolly toad the spare wire connects the toad brake lights to a cab light so that I know when the toad brakes are/are not applied.
Dolly towing is generally more useful for multiple different cars. Suggest you have DW deal with the car for towing or at least she provide significant help. Then you will both be able to determine any possible future changes.