I have never gotten completely comfortable on my RT's seat, it slopes to much forward. On the high position it was better, but too tall for my legs. On the low position it sloped forward even worse so I didn't care for that either. I am a cheap bugger and didn't see spending $750 or more for a seat I couldn't try out. On Ebay I ran across these rubber bumpers for the front mount of the seat, They advertise them to lower the seat. They look like the stock mounts, but the center hole is offset so depending how you turn them on the mount they will lower or raise the front of the seat about 3/8". I put the bracket in the low position, and adjusted the rubbers up and put the seat on with the rear supports in the low position. I put on a couple hundred miles yesterday and completely forgot about the seat. I guess it worked! I was always fidgeting, trying to get comfortable, but not yesterday. Best $8 I have ever spent!
https://www.ebay.com/itm/2X-Rubber-Rider-Seat-Saddle-Lower-Kit-For-BMW-R1200GS-LC-ADV-R1200RT-LC-14-19/333629614803?hash=item4daddfead3:g:C3sAAOSwUM5e7GHM
https://www.ebay.com/itm/2X-Rubber-Rider-Seat-Saddle-Lower-Kit-For-BMW-R1200GS-LC-ADV-R1200RT-LC-14-19/333629614803?hash=item4daddfead3:g:C3sAAOSwUM5e7GHM