I have the Bestem driver's backrest on my 1300R. Different seat, but the Suzuki isn't quite a 1800C either.
My sig pic and avatar show it, though not great. Personally, for the money it's a great buy. I didn't find it pushing me too far forward. I was just glad to find something that worked with the stock seat for an reasonable price and it works as expected.
I don't know how it would hook to the seat on a C, there must be some differences. Mine looks just like the one in the above picture. It attaches to the underside of the passenger seat.