By guest you mean someone who will work for beer and later invitations?
How bad would it be to staple in paper fronted bats to the floor joists from underneath?
If you are gonna build up the floor with foam and plywood you could add poly tubing and a tank to give yourself a heated floor plumb it to a water heater or a tank by the wood stove or propane heater...
Unless I misunderstood something in the description, the paper side goes n the warm side of application.
