Dennis- gotta love those dogs! Cute as ever...
Joe- the metal doghouse underneath is all your support. The cover on mine like most is made of plywood, pretty thin. I added extra insulation over the metal cover glued down, and under the carpet. Rubber stuff used as underlayment for laminate or hardood floors. Seems to have cut down the noise and hopefully will do the same for the heat in summer. There was nothing under the carpet throughout the driver/pass area. Not even padding.