I posted this on your entry (thread) on another site.
On my first 5er I was learning all but using and storing a 5er. I would put the 5er away in the storage yard after every camping trip and when I went to tow the 5er out the battery would be dead. The electrical parasitic in the camper would drain the battery dead.
What I found out was I could simply plug in the camper umbilical cord to the truck’s 7-way plug and start the engine and used the alternator with the truck electrical system to rise the legs on the camper with no issues what’s so every. By the time I got the camper home from the storage yard the truck alternator would charge the campers’ battery up enough to power the legs down without be hooked to the truck.
At least on Chevy’s and Ram trucks this will work I cannot say about the ford trucks since I will not use one and have no experience with one pulling a 5er.
I have since learned to have a battery disconnect switch and use this; mine complete disengages the negative cable from the battery.
2016 34RL CC; 2008 Ram Mega Cab 2500HD, 6.7L, 68RFE 6 speed, 4X4, Smarty S67