the "110" in the part number is the psi rating of the piston, so no wonder you can't compress it by hand.
Sounds like the wood of the bed frame is too soft for the stress. Had that problem with a 96 Southwind we owned some tears back. Can you bolt it through the side? Or maybe glue a hardwood block to the bed frame and screw the supports into that.
2004 American Tradition; 2014 Buick LaCRosse
Homebase in the Ocala Nat'l Forest near Ocala, FL