Very cool. Thanks for sharing.
I don't know how the Prius system works but with our leaf we can sleep with the AC on and it uses about a 1/2 KW per hour (or less depending on the temp obviously). I would have to measure but I think the leaf would be to short to stretch out.
I think that N200 nissan E van would be a good candidate for a travel van although you would want to choose routes well populated with fast chargers. Alas it is yet another EV not available on this side of the pond. Seems to me they are coming out with a 50 KW version in 2018.
Happy trails.