Not 100%, but you might evade company car tax if it is a crew van without rear windows. Vauxhall sorted it on the Combo r.e. VAT but not sure if it also applies to car tax (logically it should but logic never applies to HMRC).
http://www2.whatvan.co.uk/relatednews1.asp?id=4720
But windowless van would be pretty dismal for rear passengers on long trips….
New long Berlingo (L2) http://allworldcars.com/wordpress/?p=13317 and Transit Connect can be got as windowless crew-vans with a sliding bulkhead to keep rear passengers and cargo separated.
Dispatch (Scudo etc) Combi is also quite nice but maybe not fast enough for you (we have one as family car).
Caddy was overpriced, over-trimmed for MTB duties (Life) or under specced (window van)and discounts / dealer attitude were dismal.