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.
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.
You could look into a Hannigan sidecar. Hannigan has a sidecar specifically for the GoldWing (GTL sidecar model). The website does indicate that the sidecar has quick disconnect hardware. Here is a link to their sidecar page: http://www.hannigansidecar.com/content/sidecars.html