Aaagh - I seem to remember you asking about my LWB, although how serious you were about an S3 rat, I'm not sure,

but perhaps I should have given you a chance
Anyway, Rex has gone to a very nice guy in Sheffield, and I hope he's happy there - I do miss him as he was the one I could jump into and drive without thinking as he was well sorted and so light to drive.
Now I've got two lumbering beasts, Steptoe with all his heavyweight additions & 6 pot Diesel slogger of an engine, and my Carawagon (not so much of a slogger now with the 200TDi & 3.54 diffs

).
Hopefully, if you're serious about a LWB conversion, you'll see plenty of ideas here.
MrLeadfoot has loads of pictures in a gallery - lots of different conversions
viewtopic.php?f=10&t=18#p49
There are a number of ways to convert the roof - my favourite is an Australian couple's idea - hinge the roof at one side and flip it over 180 degrees with a 'pram fold' tent opening with it. That gives a double bed in the roof, and loads of space in the vehicle. I was in the planning stages of that, and even had a single skin roof lined up to start the project before my Carawagon appeared.
Perhaps I'll still do that with Steptoe, once all my other projects are finished
Cheers,
Robin.