Looks like you are going to have to learn real fast what "less water is more" is all about. Wet yourself down, shut water off, soap up, turn water on, rinse off, turn water off. Dishes - Little soap water in the sink, wash dish, rinse shut water off, repeat. These tanks are not that big. Only other thing you can do is always get a full hookup site and keep dumping but make sure you fill back up before you want to dump your black tank for rinsing purposes.
2013 Puma 30DBSS (Parked at Seasonal Site)
2001 Ford F-150