The toad should not use it's battery for anything other then Aux. braking device if equipped and needs power to run.
The lights are powered from the coach chassis system and should not be effected by toad other then a little additional load.
This should be a non-issue. I have wired in driving lights to front of coach. They are on when the ignition switch is in run position. I installed a switch to shut them down manually if the need arises. We virtually never drive at night.
He may want to wire an indicator in the coach to show that the lights are on so when you shut down for the day it will remind driver to shut the lights off.