Hello, Here is a link to the National Highway Transportation Safety Administration, (Federal Government. Reviewing this link may show you what you want in a car seat.
https://www.nhtsa.gov/equipment/car-...-booster-seats
As for a Class B Van at 20K, is not impossible. The point is it will be USED and maybe much more than you want. My suggestion is if you must have a van why not think of a new full-size van with say two rows of seats. NOW ask yourself and your spouse what you will both need and do a conversation. You can also use the van as a run around vehicle, schools, and alike sports activities. Plus it would be fun doing a conversation.
Off the top of my head a place for all four of you to sleep, window blinds/curtains. Port-able potty. In cast into a box, you can use to seat on when no in use. Blader tank for holding water you can move about.
So ask yourself what all could you use a new van?
A conversation starts with some good friends as a fun project. But get your ideas on paper first. Just my thoughts.
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2021 Coachmen Galleria 3500XD, 24FL, with Li3.
We are H.L. and Jan, from the Sunshine State on Florida's west coast.
"Remember every camping trip is an outdoor adventure and begins and ends with a road-trip. Drive safely with your family cargo."