If you’re feeling motivated, and since you’ll have the seat off the uni, take a look at the ghetto seat flattening folks are doing: The world's second best unicycle seat (for tightwads)
The Nimbus Gel is my favorite so far for flattening, foam requires minimal work to be comfy.
I have some ideas for how to improve the mounting system, one of which would be to place the mounting point in the same location as the grab handle.
See if this makes sense: So from the KH plate, make an elbow that extends vertically in front of the seat, then the bar end would be at the same height as the seat/grab, also it would give you more effective “grab” for your hand.