I am thinking with the 2 bunk beds that opens outwards, you would be letting the exterior temp in anyway. As for the floor cold walking around.. I plan to pick up a garage rubber mat at COSTCO or SAM's Club and cut to fit with velcro underneath to keep it from moving around.. Wife wants to just get a nice area rug to put under the benchtops and sofa.
Not sure if you have seen the bunk outs, with fully loaded, you can still open the Queen side Bunk outs beds outward on both sides and have 2 Queen to sleep without having to move anything.
KS