I checked Classic Industries in Australia. They make hitches for lots of Guzzi's. I saw a Norge hitch, but not a Cal. 14.
You might shoot them an email and see if something is in the pipeline.
There is a Dutch hitch. So it can be done.
http://www.tourmaster.nl/en/9411941/motoguzzi-california-1400-touringIf you have a good welding shop, or a friend who is a wiz at fabricating, hitches are not hard to make.
The lower arm is usually bolted to the footpeg mounts. The upper arm runs from the top of the shock mounts.
I Googled "Trailer Hitch Fabrication" for Denver and came up with several names.
Maybe get some close ups of the Dutch hitch for ideas.
Then ask them to see what they can do.
Mike