Just an idea, post up on ADVrider in Flea Market.
Call Bushtec trailers for leads, or any thoughts Todd may have there.
Call Electrical Connection, ask Lewis for ideas or lead.
There's a couple moto-trailer groups on farcebook, don't have those names at the ready, but you should be able to find them with Search. Bushtec has a group there too.
Looks like you are in for a quest... get around on the internet, and something will turn up. Ask others for thoughts I have missed here.
I found one in our For Sale forum, but it didn't happen instantly.
Perseverance will be rewarded - now get after it like you're serious!
EDIT: pricing a hitch for my 1250 GS/A seems to be right at $500, but as it's a new bike, hitches are available.