Re: The HOLYBUS
It get's pretty cold in Central FL. My grandmother's pond used to freeze over thick enough for the hunting dogs (big hounds) to walk on. Back on the late 60's my cousin walked on it once when it got cold for so long. He was about 11 or 12 at the time so he had to of weighed over 100lb. Come to think of it, some of the hunting dogs probably weight more than he did! And that was in Pierson which is farther south.
Besides insulation isn't just to keep the warmth IN during the winter... it also keeps the warmth OUT in the summer. Carpet does not insulate as well as you might think... as I sit here in my stick-n-staples RV with cold feet on my 1 1/2 " thin insulation with 1/2" plywood on top and a layer of carpet (commercial grade) plus a thick braided rag rug over that. My feet are cold and it's 53*F outside. As some one who camps in public (also known as DIRT) campgrounds a lot, carpet is a horrible mess to keep clean. The sand gets down in it and cuts the backing causing it to break down faster than normal.
Skimp on most anything else except the insulation. Almost anything else can be retro fitted.