I sold a Caravelle via ebay before Christmas. It was a W-reg with 198k on the clock, a body that looked good, but needed some serious work, and a fairly serious oil leak. I listed every problem it had in the most honest possible terms, and had people contacting me instantly to ask if they could by it off-auction. On-auction, it reached £1200 before a man came who had seen it advertised elsewhere, and bought it for £1500. I was extremely pleased.
Only days before, I had bought a different Caravelle myself off ebay, and it has proven to be excellent.
I don’t know exactly what sort of advice you want, but I would definitely try to sell privately – even using ebay. Equally, take a look at the VW T4 forum (it also covers T5s), and see what people are looking for.