Large Mechanical Actuator - Need Advice

I am trying to get an actuator that is 3 pinholes wide and 4 pinholes tall. The length is good for my purposes, but the issue is that I am having issues with the “piston” needing to have at least one row of plates on the bottom to secure it together, which results in the bottom needing one plate or half liftarm offset to hold it together. Right now I’m using plates and liftarms to hold it together which does work, but it’s bulkier than I would like and I feel there is a simpler way to do the...