First thing I noticed was some water damage to the subfloor, which is to be expected after 20 years of use. It will be replaced with a regular ½ inch plywood panel.
The wood is attached with a couple of metal screws to the metal floor.
The rear 4 feet doesn’t have any insulation at all. That is something I’ll improve on with the new underlayment.
The remainder of the carpet is a snap, because there is no ply involved and the ½ inch insulation remains in place. I’ll leave the carpet in the cabin in place, until I’ve decided on the replacement material.