Bad idea - there is no down pressure when lowering the mast assembly - gravity does the work - lowering is controlled by a flow regulator. You don't want the issues associated with - mast sections, carriage, cylinder collapsing unless you have a big check book and lots of liability/workman (women) comp insurance. Get a skid steer loader. (ask a authorized dealer if it is OK first) or something similar or hire a retired Sumo wrestler to stomp it down - if OSHA approves it. And keep a Philadelphia Lawyer on your payroll.

I'm certain there is a trash compactor around to fit your needs - they are all over for paper, cardboard recycling and even in my kitchen