James ... many of us have bought the metal floor vents that close like in mobile homes. Alternately we've bought the magnetic vent covers to lay over the floor vents. The floor vents go right back to the furnace and the furnace just sits in a big space that shares your storage area and also is not sealed into the underbelly. Thats why your storage compartment is always cool when your A/C is running. Here's an old post of mine ... I's imagine Keystone has not changed the design of the dropped frame since 2011.
http://www.montanaowners.com/forums/...rms=Insulation