Even on the LWB the back isn't big enough for what you want Ian if you still want to carry your pressure washer stuff in.
SIL has a T220 LWB (825kg payload) and that is the same size as the T230 (900kg payload). It has a 500 liter tank in the back and with his wheeled hose reel there isn't much space left to the back doors.
Your really should be looking at something bigger, ie Transit T300 in a MWB length IMO.