I too, want to take my bike along on trips, it's a Yamaha Virago 1100 that weighs about 475 lbs., a little too heavy for one of those rack type carriers on the back of a Vanagon, IMHO. A while back I saw a motorhome on the side of the highway, had one of those across the back type racks with what had been a very nice bike on it. Problem was, the bike had fallen off and been dragged for several miles! This would be pretty obvious in a Vanagon, much less so in a massive motorhome. Anyway, my choice is a 4x7 trailer. I have been anxious to hook the bike/trailer combo up to the Vanagon and take it for a test cruise to see how the Vanagon (Westy) can handle the load, which I'm guesstimating to right around 900-1,000 pounds. I especially want to see how it is in the mountains, as one bike event I plan to go to this summer is at Snowshoe West Virginia. Just been waiting for the weather to warm up enough to go for a test drive. Another reason for the trailer is for other misc camping gear,
 like the Easy Up, chairs, grill, etc. I used to have a really small trailer (built from a Harbor Freight kit) that I towed behind my Bay window Westys. It sure was nice to be able to haul all the bulky crap in the trailer leaving the interior uncluttered. Another advantage to  the trailer is packing up when all the stuff is wet, you don't have to stuff all that wet crap inside your camper. My Westy and bike can be seen at    http://veedubguy84.com    Jeff