These type of springs are also known as 'Belleville' springs.
We use them in formula cars in the front anti rollbar to change the stiffness.
The possibilities are hugh because you can change stiffness by changing the orientation of the rings or by changing the amount of preload.
I think it is defiantly worth to test it.

If you could get the proper size, let me know I think I want to try them aswell.
It should be a direct fit if you would use 4-5 rings depending the orientation.

<<>> This would be a stiff setting.
<><> This would be a soft setting.