I use a double carrier, but I still have to use an extension.
I carry the bike on the rear tray if I want to retain access to the back of the van. As a bonus this give me extra space for coolers.
I do much prefer the bike carrier over a trailer. Less to go wrong on the highway like tires and wheel bearings, and I don't have to worry about lane restrictions (WA and CO) or lower speed limites (CA
).
Downside is it puts a lot of weight on the rear axle, and tail-swing is prominent.
A Class-5 (not to be confused with the "V5" manufacturing standard) is a must if using a bike carrier with an extension.