I also have a Yamaha XT250 that I carry on the back of my 2005 2351. The XT is a perfect light bike for the 2351. I added side and top metal storage, GPS and front bars.
I modified a
http://www.magnetatrailers.com/receiverhitchaccessories/dirtbikescootercaddy.html I love the carrier because I can lower it to the ground which eliminates the danger of dropping the bike while putting/strapping it into the carrier. But I had two problems: the weight lowered the back of the 2351 on steep driveways so that the carrier dragged and the side to side rock of the carried was worry some on poor roads. I did solve both of those problems. The unit has been driven 1,000's of miles with the carrier.
I hate airbags which can cause more problems then they are worth.
1. I added Sumo Springs and Bilstein shocks
2. Welded stabilization outriggers supports on the carrier to the OEM bumper and use 1" receivers to connect them when the carrier is in it's highest position.
3. Welded steel roller wheels to both sides of the OEM bumper hitch
4. Welded a steel tube from frame to OEM bumper hitch to increase the receiver stability.
5. Welded a skid pad to protect the plumbing.
I don't have a picture with the actual bike on the carrier but here are some of my mods.
I also rewired all my rear lighting with LED and repositioned the 7 way connector. I did not like the OEM wiring and position of the plug.