Used to tow a 17ft tabbert (very big n heavy van) approx 1300kg unloaded with my old series 3 and with our lightweight, never fast but used to get all over the place slow n steady (50ish).
Unless you are really severe with your gear changes and braking the van will be fine, i remember one company (but not sure who) did a spring cushioned tow plate but never needed one and never damaged the van.
Go ahead n do it, just take your time
Cheers Steve