>>309534524
Got it working with constraints, had to make some new bones, change some parenting and weight painting but it seems to work pretty well.

Front Piston
1 rotation constraint (slide bearing is offset from rotation origin)
2 aim constraints
Back Piston
2 aim constraints

This means
2 rotation constraints and 8 aim constraints for both legs instead of 
8 dynamic bones
24 simulated dynamic bones
8 colliders
16 collision checks

Overall an great increase in performance!

Time to put it on the avatar and see how it looks in VRC later today!