I would recommend a guard that fits on teh rear bumper to give protection. You can get black or stainless. I woud also get the wrap over type,
http://www.ebay.co.uk/itm/VIVARO-TRAFIC-PRIMASTAR-3D-BUMPER-COVER-PROTECTOR-/171044984907?pt=UK_CarsParts_Vehicles_CarParts_SM&fits=Model:Vivaro&hash=item27d313584b . I bought the flat type but it doesnt protect the curved edge.
Sill protectors are available too in Stainless and saves scuffing paint work when getting out of the van.
Be carefull if you want a Bull bar as there are not many that fit the new vans due to the air con pump being in the way. If you do find one let me know.
Side bars look cool but can drag if you go over uneven ground on site.
You can get Stainless front and rear bumper bars etc to add protection.
I went for heavy duty original cloth seat covers, took a while to fit properly but most people look and think they are the original seats.
Stainless door handle covers are available and I find it help keep the van clean when you open the doors with grout or adhesive residue on your hands as it wipes off easier than the black plastic handles. They just stick on with scotch tape...very sticky !
Get a USB stick and down load your music collection on to it. Stick it in the USB port on the dash and you have all your music to hand. Great idea.
I bought some extra original interior roof lights for the rear to add more light.
Finally finish it with one of these
Prefix registrations search. Searches prefix style registrations
http://dvlaregistrations.direct.gov.uk/buy.html?plate=PO10 OLS&price=399