It was hot in Nebraska so we kept our front curtain pulled all week to help keep the sun out. What we didn't know is that two snakes liked the heat and found their way in and enjoyed the dashboard. ...
Speaking from experience, when camping keep all outside storage bay doors fully closed. Where your sewer hose, water hose and electric cable exit make sure there is no open area around them. I pack rags sprayed with insect repellant around them. In 40 plus years of travel we never had a snake get in that I know of, but I have found them on the under side on frame rails and in the engine area.