I have a 28" -29" inseam, and struggle a bit with the seat height of the F6B. I have been riding with a Mustang seat since I purchased the bike (a 2016 model). The Mustang seat helped the height issue a bit, but it is also very hard, and can create back pain after 200+ miles of riding. Even the addition of an AirHawk seat pad hasn't helped all of that much.
I enjoy doing very long rides...including Iron Butts, but I am going to be limited in such efforts until I figure a seat solution.
Custom seat work on original seat is a good option. I used Bitchin Stitchin in Denver CO and I’m 100% happy with the seat. I had the opposite problem you have as I wanted less knee bend while seated.
You can do two or three things all change your bike.
One Get the link from Lowerwing.com
Two after that do whats called slip your forks.
Then get yourself a good seat. The seat and the link are where
the money will go.