After a while the truck will start to load shed some non-critical items such as bunk lighting when the battery draw becomes excessive. If I were you I'd look into getting a APU.
I just leave mine on. My truck has a low voltage cut out so when I'm at home it will eventually shut off the current. I have the fridge, my cpap machine and sleeper fan going and all 3 don't draw the voltage down enough to set off the cut out during my 10 hour break when I don't idle.