First we tested the convoluted bellows with an existing 500X unit (20 SCFM). The inflation speed was acceptable for the money it would save, but the deflation speed is too slow due to the small body ports.
Second we tested the bellows with the M2d proportional valve (60 SCFM). It isn’t a closed-loop system so we can’t control the pressure and the M2d is half wasted because it is meant for double-acting actuators.
So in the end I think the E22 (100 SCFM) will be more than enough and it has full 1/2 FNPT exhaust and is about $200 cheaper than the M2d. I will install the 500X units temporarily for testing and so I can lift the platform up and work underneath without jacks.