Perfect timing, just popped in quick to check my inbox and saw this post.
I doubt you will find anything like the Goldwing seat for the M109R.
I do have a Corbin passenger seat for sale.
The Corbin seat is much nicer than the stock seat and you can also buy a integrated backrest for it from Corbin if you like.
I am selling the seat for $225 delivered to your door in the lower 48 states of the USA.
Seat is $425 if you buy it new from Corbin.
Photo of the seat is below.
If you decide you want it or need to contact me please email me at [email protected]
I only check in here about once a week to see if I have any PM's, so if you respond to this message or PM me I will likely not see it for a week or so, email or Facebook is the best way to contact.