In reply to iksander:
I'm a short arse so height never been a real issue but my high top Transit has plenty of height - just watch the floor has not been raised too high (mine is up by 3 inches to allow for seat attachments underneath - it makes a big difference)
With regards the bed, if size is a major issue you'd maybe be better sorting out a custom made arrangement - the 350 length Transit should be big enough for a 6ft plus bed and then storage space at the back - mine has a storage area and a bathroom in the rear and there is still space for a typical caravan seat/bed longways behind the driver.
I'd recommend converting a mess unit / welfare van - mine came at the same price as an empty van but with toilet/sinks/heaters/electrics/storage/batteries etc all fitted. You should get a good low mileage Transit for 7k these days.
Post edited at 11:51