I tried Cleveland Moto, they didn't have the Givi windscreen or installation kit for it. I did however score the luxury seat for the Grand Vista there. Way more comfortable than stock seat. It was there last one, probably had it there for years since they wouldn't ship it, pick up only.
I have the captain's seat on my scoot. Yep, it is more comfortable than the stock seat. When I bought my GV from Cleveland Moto back in 2020, it was pictured with the captain's seat. When I went in to look at the scoot, they had switched out the seat to the stock. I asked them where the pictured seat was, and they hemmed and hawed, and said they would switch it back "at no cost." I told them, right, at no cost, because you advertised the scoot with the better seat. That's the only issue I've had with them. Other than that, they are great to work with, and the service manager knows his stuff. Good luck looking for the bracket. You might want to talk to the service manager - I think his name is James - and see if he has some suggestions.