GLK's GLX-FC 209 landing gear model can be fitted to all models of large bikes The landing gear is a combination of rigidity of aluminum alloy and special reduction gear, and its total weight is about 11kg. It's a very robust product that has no problem supporting the weight of a large bike...
To answer the original question, I found these comments in the YouTube comments for the video posted that are about ten or more years old:
"They are no longer in business. Were wiped out with the hurricane in New Orleans."
"Wow, seeing this video reminds me of old pre-katrina days and a childhood watching my father's passion. Wing Landing Gear was my dad's business. He's the guy riding the motorcycle in this video. I have read a lot of ignorant comments that are incorrect and some bright ones too. Setting the record : The cost of landing gear was $3000 if I remember correctly. A quality trike setup costs double that."
Now, one might take to doing some additional research in that S. Korea variant of this system. It's a fairly new variant of the 'training wheels' process.
One could also consider casting a wider net for information on this system. After all, not every Goldwing owner is a member of this specific forum...
c) goldwing riding group near you (You're on the FL pandhandle - gotta be somebody out there close to you...)
d) There's around six goldwing-specific forums out there; again Google might help you find them.