I use to have a Ca Sidecar. It was very nice. Having owned one I do recommend them. Was kind of a pain to put on and off, but that was quite a few years back. Ca Sidecar now says it takes about 15 mins to do.
Here is what they have to say:
Installing your sidecar is made simple with the 4-point mounting system, and most owners do the job themselves. And if you find you would like to ride solo one day, you can go from 3-wheeling to solo in less than 15 minutes, thanks to our unique and handy quick disconnect system.
Check them out here.
http://www.californiasidecar.com/sidecars.htm
Edit:
ouch. Just looked at there site and it does not list the 1800 only the 1500.
Mine was on a 1100A when I had it. But I would still give them a call.
Now that it is obvious I have no idea what I am talking about I will shut up now. Have a nice day.