You're on the right track, but expect everyone to get used to the luxury of the camper pretty quickly.
Coming from a family that tent camped forever and after having a TC for a while, my older one actually complained about sleeping in a tent this summer! Lol. (I didn't cave in to him, but in his defense an animal, I think a pack rat, got in their tent and p!ssed under one of the bed rolls! I didn't believe them, told the kids it was their dirty socks that stunk, ahah.
Camper is super spacious when the kids tent it. Then all their "stuff" is out of the camper.
Storage wise, our short bed capable AF seems to have plenty of storage. We can pack clothes for 4 for most conditions, over a weeks worth and everything else needed for extended trips pretty handily. Honestly the only thing that really gets in the way is drinks. A weeks worth of beer, soda, bottled water etc takes up a lot of space but disappears gradually.
Tank wise, we have 50ish gal water, I think 50 gray and black tank is much smaller. We can roll for 4 days 4 people including quick showers most every day before running out or filling tanks.
Sounds like you're looking smaller though so storage and tanks will not be as large likely.