Dumping...A lot of states have dumps sites at their rest areas. The app mentioned above should give you what states do and don't and you can plan accordingly.
"Timing tank limits" you'll get the swing of that real quick... after making a few unplanned trips to the dump station. And when school is out and weather's good, Sunday afternoons in the summer you might have a long line at dump station.
I've found spending the $5 or $10 to dump is OK but that's only 1/2 of $$$ spent. The other 1/2 is wife or grandkids and me I guess buy "stuff" at their store. Re-fueling and dumping ends up being not so inexpensive. Like parking for "free" at casino's doesn't turn out to be "free" sometimes:B
That's one reason why we dump at rest areas as much as possible. And many have area for kids to work off energy after being cooped up in vehicle. Of course you have to make sure everything is safe. And if your a cheap like this grandpa is, The money saved by using Gas Buddy (versus Flying J and Pilot) and using rest areas to dump goes towards the grandkids spending money. So they want to save also and they really get into it and get to use their math skills. First postcard home is usually how much "they saved Grandpa".
Water use... Took us a while to really get into conserving water to make water last longer. After you run out couple times, learning to conserve more will become higher priority. Until then, suggest keeping couple gallon jugs stored somewhere, just as back up.
Don't depend on your gauges to see when your tanks are full.