I was looking at the Peugeot Expert and the identical Citroen Dispatch. Neither are as large as a Transit or Vivaro - being able to stand up in these I think is always a plus and not possible on the Expert / Dispatch, but would cater for most shows upto £5K. They come with the steel bulkhead and there were some good deals to be had on the slightly older version with different engines and a variety of access doors etc.
As an example... gone now but was available last year..
Auto Trader UK - PEUGEOT EXPERT 900 HDI 1997cc