You can run down the tow vehicle battery if you leave the cord plugged in.
This is not a problem on my FORD TRUCK as the battery connection is under a relay control and is switched OFF when I have my truck ignition key turned off.
I'm sure other trucks have the same standard feature - At least something to check in your case... You can always just pull the 7-way connector when you stop if in doubt. Of course I would leave a note on the steering wheel to remind you to hook it back up before you leave the next morning haha...
Roy Ken
