hi ponder,
here are a few pix you asked for.
at the front of the seat at the hinge point you can see I added angle iron to move the seat back. I measured and I moved it back 3 1/2" from what it was when I got my little girl.
the springs I got from a local hardware, i got 3 sets at different wire sizes to adjust comfort. I can add add a stiffer pair to decrease motion. Motorcycle seat springs could be used and are best found on the net, no local bike shop had them here.
I know your tractor is most likely not even similar, but you and friends I'm sure will coustom make what you need.
Good Luck, Be Safe, Have Fun !!!
Edit: forgot to add, notice the Shifter and High-Low selector are reversed letting my size 12 boots move through for super easy mounts and dismounts.