I've been wanting to get a side car so I can take my Rottweiler with me since she just loves to go with me everywhere! I feel this is better/more stable solution than using a trailer. Especially for a high energy dog like her. :-)
Has anyone seen or done this mod? And of course the next question would be, where is the best place to find an affordable one?

2013 Breakout FXSB

 

You can put a sidecar on most anything. Softail will require install by a real pro.. I had one on my Fatboy for a few years.
Take you time and make sure you willing to spend the cash.
You could likely purchase a complete Rig for what you will end up spending. Stop in USCA forum.

https://sidecar.com/forum/