Ok, I've been thinking about this for a bit as well.
We started off with a Malmos (Towsure) Towbar mounted rack - it didn't hold bikes very well but didn't cost a lot but you had to take it off to open the tailgate (costs about £50) but you need a light board.
Next we bought an avenir vermont as it goes on easy - high up, doesn't obscure the number/lights etc and you can open the tailgate with it on (without bikes) and still tow a trailer Cost about £90.
The other option is a Fiamma Pro C - looks very neat - Haydn Callow has posted some pics. But you need to drill holes and it looks low enough to interfere with the trailer? It can carry four bikes I think. I'd guess that with the struts etc its below £300 but needs a lightboard
But If I was doing it again I'd get a Fiamma rack for the VITO get the struts upgraded and get the spoiler cut. These can carry four bikes I believe but costs all in say £300? It can be used with a cargo bag, does not need a light board and towing is an option.
Last option is the Bakrak and Thule bike carriers that use the tow mount, but you cannot tow a trailer. The Bakrak looks like VFM and has some other flexible options, both need light rack?
Guess its cost versus function and use. I couldn't make my mind up so I'm sticking with the Avenir Vermont
