Thank you all for the very informative feedback.
Will look to pickup a van that's as new as possible. Also as Oldgit mentions, there's some interesting Japanese options / that can convert to Campers nicely. I've seen a few MPV's that would do quite nicely, being imports, you don't see alot on our UK roads (such as the 'Nissan El Grande' - that look a little unique, from the usual favourites).
Will certainly do this in stages. Strip. Insulate with new "walls" (Ply sides/floor). Then build up the 'accommodation' to suit.
Transporting a young family, I'd need to ensure a metal framed seat can be fitted + seatbelts. Seated securely, for potentially long rides on the road.
Was hoping to see a load of projects others have already done, however it appears Yamaha bike owners and Campers, don't mix (much).
Or perhaps ppl are reluctant to flaunt their investments over a "public" internet forum. Understood.
Again many thanks.