Two days on battery only

I've always camped where there are electrical hookups. Next week, we'll be at Grand Canyon NP where there are no hookups. We'll be spending two nights.
We have the original 12 volt deep cycle battery that comes with our 2009 TM. If we don't run the refrigerator, what are the major drains on the battery that we should avoid. Interior lights? Toilet? Radio?

Thanks.

Richard