I dunno about any of that man.
What I do know is that the absolute cheapest way out is going to be a set of 8s, 1 pump, 1 dump, 1 slowdown, and 1 check. 2 lines. Only need one solenoid, and a single switch. This is assuming the spring idea would work to retract the cylinder. best part is you don’t need a serious pump for any of this, could even grab a used one if you could score it cheap enough.