have you had a look at Fleurette motorhomes, they do a model with twin beds and a lounge that will seat between 6 or 8 at a pinch.
The dealer in UK will only import now to order, but as it is a French van there should be a few available over there. I doubt if any of the owners here will sell theirs. the model you want is the Migrateur 73LJ. their website is www.fleurette.fr
good luck in your hunt.
We are just waiting for our LMC Breezer V 643 G to arrive at the dealers from Germany. It is on the Fiat base ( as we need an automatic). After months of looking at other vehicles we chose this for the layout exactly what we knew we needed and the apparent quality of the finish. Can't tell you what it is like in practice yet as we haven't got it yet - only a few more days and getting excited now.