This is for the low seat position..
I did this mod today. Thanks Tony for the idea. I pulled the old Lowes rubber bumpers and replaced with the Road Star cushions. Everything works nicely.
As for drilling the hole in the rear support, you can remove this with 4 bolts. Two of the bolts are hex head and the other two are hex bit(at least on mine). You may have to remove the passenger seat(I don't have one on mine, just a rack) to get to the hex bits.
Pull the piece off and turn it over. Mark the hole in the middle and drill. I then used some dielectric grease to help ease the cushion in.. lol, then use a little on the top of the cushion to help the seat slide in a little easier. Yea I know... lol
Replace the support and seat and go for a ride..