Setup for Boondocking
Yes, it's true that most RVs come "Self Contained" when you buy them. But to make that self containment last away from full hookups for more than a day or two for a family size group, you either take extreme conservation/minimalist measures or you set your rig up to accommodate your needs - or both.
Campsites that are described using the words 'primitive,' 'dispersed,' 'rustic,' 'dry camping,' or 'boondocking' are a tip off that you're going to need more equipment than your RV probably came with from the factory. Even a lot of the state and local level campgrounds have an electric hookup at your site, but you have to drive across the campground to a dump station to dump your black and gray tanks and fill your fresh water tank - unless you're equipped for boondocking.
You can equip yourself frugally or generously.
Most people start with frugally.
Solar is great, but doesn't replace a generator if you want reliable power for your normal activities while in your RV without being tethered to a 30a or 50 amp electrical hookup.
A warning about generators: they get stolen ALL THE TIME. The better your generator, the more likely it's going to disappear within seconds after you turn your head away from it. Lock it in the back of your truck when you're transporting it. Lock it to your RV when you're running it. You can use a steel cable with sealed loops on the ends and a good padlock or whatever security method you prefer. But lock it up any and every time you're not looking right at it.
Replenishing your fresh water tank
There are lots of helpful ways of conserving, but if you're not hooked up to a constant water supply you'll go through fresh (potable) water - lots of it.
Fresh Water Pump
"Gravity pumping" rarely turns out to be a reliable, satisfying method. These pumps are cheap and easy to set up and use to get the fresh water out of your Aquatank and into your RV's fresh water tank. (Some motorhomes and 5th wheels already have onboard pumps meant for winterizing and dewinterizing that can be set to "Tank Fill." If you have one of those, you probably won't need any of these pumps.)
Emptying your waste tanks
Some boondockers go to great lengths to keep from filling their waste tanks, and good for them. But if that isn't an option for you, you still have great options. It's a dirty business but perfectly respectable, healthy, hygienic people use waste tank totes every day.
Dumping black and gray tanks is usually done with gravity. But that only works when the receptacle you're dumping into is physically lower than your waste tank outlets. There is almost zero chance you are going to lift a full 42 gallon tote into the back of a truck - certainly not on a regular basis. So you have to pump it uphill to your waste tote. Gray water is usually all liquid, so a regular pump can handle that. But black water has more...solids that would block up a regular pump. So they make what is called a macerator pump, which shreds the solids while pumping the black tank into your waste tote. Some high end RVs have onboard macerator pumps, but most don't.
Flojet Waste Pump:
This model is by far the most trusted and most used macerator pump among boondockers.
So the big warning for boondocking is this: RVs get stolen very often. It's a horrible thing to do to someone, but there are predators out there doing it as we speak. It's heart breaking to talk to someone it has happened to, or even see a post on facebook about it. If you unhook from an RV and drive away from it, and it isn't in a hosted, gated campground or RV park, you will definitely want to take some precautions. Some people have electronic surveillance systems with real time cameras and alarms that communicate with their cell phones and notify law enforcement in the event of a theft attempt. Others make a habit of leaving someone in the RV while they drive to a dump station or potable water source. Sometimes the people left behind with the RV are armed in one way or another. Whatever your preferred security method, please, please don't leave your RV susceptible to being stolen. They are almost never retrieved, and when they are horrible things have happened to them in the meantime and irreplaceable items are long gone.