On my Rockwood, I have a kills switch underneath the fridge. All winter, I never disconnected the battery and just used that and they kept a full charge.
I assumed they had no draw but, last camping trip, I was goofing around and discovered the slide out control does work even if totally disconnected from shore power and the kill switch was on...I was amazed! (I don't know why they would wire it like that, but it is.)
In my last trailer, I did have to disconnect the black cable off one of the batteries to ensure no draw was taking place. (Some people connect a simple switch to that.)