I’ve got some ideas of things that would make vanlife a lot easier:
A cassette-style water tank that allows fixtures to be plumbed up to it. Many vanlifers do the 6 gallon water jug shuffle both for fresh water and for grey water. For the fresh water, it could even be as simple as a water cooler jug receptacle that can be built in. For grey water, something like Thetford’s or Dometic’s cassettes, but with pipe inlets instead of a toilet fixture. Bonus points if you can come up with a housing that uses those existing cassettes.
A “universal” charger for the battery bank, that can take input from alternators (14v-ish DC), solar (up to 75v-100v DC), or AC (both 120v and 240v). I think EV charging stations are way underused by vanlifers. Some may argue that an ICE van shouldn’t be allowed to use an EV station, but the whole point of EVs is to be better for the enviroment, and vanlifers have much less of an enviromental impact than someone living in a home or apartment.
Maybe not “real product” enough, but a set of DXFs/paper templates for wall, floor, and ceiling panels for any of the common vans (Sprinter, Promaster, Transit, E-Series, Express/Savanna) would be a huge help to many people. Vancillary has shown that selling a paper template (cab shelf) is a viable product.
A 12v mini-split style AC system would be awesome. I’ve yet to find one in the 3000-5000 btu range that would be perfect for most van builds.
Maybe more if I think of them…