I would say navara but not many cheap ones around as the engines fall apart 😉

Odd suggestion but can be had for much cheapness and they work well off-road: http://www.ebay.co.uk/itm/Land-Rover-Freelander-TD4-SWB-Van-BMW-Turbo-Diesel-Motd-Low-Reserve-Commercial-/271878082776?pt=LH_DefaultDomain_3&hash=item3f4d3250d8

Only thing that is going to stop it dead really is the electric fuel pump in the rear wheel arch. 30 minutes to change and £180. All the other faults like electrics and VCU won’t stop you getting around a work site.

But head says old bomb proof Mitsubishi/Toyota/Isuzu