Watched this this evening.
Can't deny... I didn't like the Billy the snail camper
The cattle carrier thing ... Liked the inside but it looks like a monster to drive recreationally (looks well over 7.5t ?). Maybe end up being a nice summerhouse/garden retreat?
I think as a self-build, Trevs base vehicle choice is probably the optimum between max space with usability within European roads (go US and double it )