How long can you realistically dry camp?

Never having dry camped before, we plan to do so on our trip out west this summer. We'll be gone for 3 months, and we'll be looking for ways to camp a little cheaper for some nights. We have a generator, but not solar. I'm trying to understand how dry camping works. How long can you realistically stay out without dumping? I guess we'd have to use mostly paper products, eliminating dish washing, take fewer showers, etc. Can someone please give me some sense of how you need to modify your lifestyle in order to prolong your stay while dry camping? In my view, I'm thinking we could only do it for 2-3 days. Perhaps there is a way to manage to do it longer? Also, since you're not supposed to tow with your water tanks full, how do you get your water? Thanks for clearing this up for me.