Paul,
The Rav's ideal 80% towing limit is about 1100kG which is somewhat below the anticipated weight of your new van.
The Nissan would out pull the Rav over all terrain and road conditions, possibly at the price of more fuel burnt.
Additionally don't confuse the two vehicles as being of the same type, the Nissan is one of many 4x4's from around the world that are farm based vehicles that have in my opinion been 'mediarised'as being the answer to all macho person's desires, (have to be pc) the Rav however was designed from the outset as a SUV 'Sports Utility Vehicle' or 'Suburban Utility Vehicle'take your pick, whose four wheel drive ability was to be used at the weekend during varied outdoor pursuits, it is a very good vehicle for this but is not ideal for pulling heavy trailers across muddy fields, although it does cope well in the usual wet Caravan Site situation. John K
ps Yes I have a Rav and a Lunar 390/2.