This isn't an option on the 1300GS (maybe it is on the GSA). My GS comfort seat only has a little lever under the rear that pushes the rear of the seat farther up from the inside, I tried it but it made the downward slope to the tank even worse.
I actually found the stock seat to be pretty good other than the downward slope to the tank. The Wunderlich seat leveling kit solved that problem fairly inexpensively. I posted about it here back in May or June.
I just installed the Wunderlich seat levelers and they noticeably improved seat comfort for me. IMO the stock comfort seat isn't
bad, it's wide and firm enough and while it doesn't slope down to the tank a lot it does slope some, enough that I'm usually pushing against the bars to maintain position toward the rear of the seat. The bumpers raise the front about 10mm which is noticeable and still lets the nose of the seat to fit into the tank recess.
I really didn't need the board because where the seat is in the recess reveals the height gain more accurately.
Stock
With...
As far as what I like;
1) Suspension
2) Power and low down torque
3) Overall ergonomics
4) Fit and finish
5) Auto lowering when the stand is deployed.
What I dislike;
1) Having to go through cumbersome menus to do simple functions rather than buttons.
2) Following cruise that slows to the vehicle rather than holding set speed. Must be deactivated every time I restart the bike.
3) The big, stupid, expensive fob that requires batteries. Give me a simple, small, mechanical key.
4) Side stand is too short making the bike lean too far, even after it lowers.
5) Replace the driveshaft every 48K? Are you serious?