Having just returned from a 9000 mile trip through Canada and Alaska we need to add some additional storage space to our 180 MPG. We would like to add full- width shelves above the windows at the front and rear of the unit. Also extend the cabinet above the kitchen area. Are horizontal structural supports located above the windows at the ends and vertical supports on the sides that the shelves could be attached? Does Heartland have any drawings that shows the location of these structural units? Any suggestions would be welcome. We love our MPG.