I have all my windows covered with silver insulating pads that are cut to shape. Works great at keeping the interior cooler when the trailer isn't in use. One thing about our trailers, the builders love to put in huge windows to let in the heat and cold.
What I had to do to my toyhauler was to properly seal the air vents to keep the cold air from going into the attic area. They did a terrible job of taping at the Voltage factory but once I corrected their sloppy work the A/C works a whole lot better.
One thing I've seen at the RV shows I work is the higher-end 5th wheels are much better insulated. The Tiffin Beacon has thicker walls and double pane glass. Also the Redwoods are very nice in triple digits but you're going to pay for the comfort.
