Some of my older hang-ons had the old type Canvas seats . When I sat in one my butt would sink a little and the support bar would dig into the back of my legs . After a couple years , the canvas would rot . I cut some plywood squares , rounded the corners and drilled some holes . I then ty-wrapped the plywood to the supports that hold the canvas . A flatter , firmer seat . I take one of my seat pads with me when I use one of those stands .
Semper Fi !