ORIGINAL: timbercruiser
I would have made the top bigger, minimum1 foot overhang,to keep most of the water from coming in the wndows and off the sides.
It now has a tin roof and an overhang. Water does not come in at all. It has turf carpet on the floor, thermometer, comfortable chairs, and the rubbery stuff you use to line cabinet drawers covering most of the windows with only slots cut in them to allow necessary shooting and visibility.