Towing a lightweight caravan

In terms of legal weight limits, I doubt there will be a problem. The first thing to check would be that the total weight of the van (inc. towbar), plus its payload, plus the weight of the caravan, plus its payload is within the vehicle Gross Train Weight, shown on the van's load plate (usually the second of four sets of figures on the plate).

I don't have any direct experience of caravan towing, but I would expect the combination will be slow and the engine will need thrashing on hills (because petrol engines produce max torque at relatively high revs compared to diesels), but others may be able to refute that.