New to dry camping

Battery is going to be your biggest concern. Conservation is the key. Do not leave lights on more than necesary. We used to fill our water tank all the time using a 5 gallon water jug. We took showers every day. Dumping gray water will be your second big concern. If there is a place to dispose of gray water, its no big deal. Either a 5 gallon bucket or one of the tote tanks work well. I always made it part of my morning routine to fill the potable water and dump the gray each morning.
Depending on age/type/condition of your batteries you should get one day per battery easily.