I am planing in installing 1/2 inch hard foam panel between the FG bottom and the new 1/2" plywood flooring. This way I can finish up the floot with lino, carpet, plastic tiles, laminate flooring, etc , nail/screw cabinets to the plywood as needed, etc. and still have thermal insulation on the bottom.
My concern is load bearing so I will leave certain sections of the foam layer done with plywood strips that support the weight
of the floor and use.
Will share some pics as we get down to construct.