We have a 200 SQ/FT upstairs bedroom that has a window unit and baseboard heater. The window is around 42" wide so the window AC skirts won't reach the entire width of the window. The previous owners had made some sort of spacers (closet door section or something?) that rotted away. I pulled the AC and cleaned up the window and now need to reinstall. What is a good way to install the unit and have decent looking and well sealed window?