Hi Daniel,
I don`t know if you`ve already got the Rover or looking to purchase one, but we did have a poster on here quite a while back that had one but offloaded it PDQ as they are well known for having a woeful torque output/curve.
I gather the engine is very smooth but needs revving to make any progress, and just doesn``t appear to be up to towing a reasonable size van comfortably.
The engine has also a reputation for being fragile, there were many instances of the crank breaking when the vehicles were being driven from the end of the production line to the car park!
Sorry if its bad news, but I`d either steer clear or look to swap if you`re looking to tow a van.