yankeeslover - In my opinion the EXHAUST method is best for pulling in outside fresh air. My BATHROOM also has an exhaust fan installed in the ceiling. There is also a pretty large size hole between the bathroom door and the ceiling. My opening is about two inches between the top of the door and the ceiling
This will allow the exhaust fan to pull air for the trailer thru the opening above the bath room door.
All you do is crack open a couple of windows on the opposite side of the trailer and the exhaust fan will pull in outside air from these these two opened windows providing most of the trailer with fresh cool air.
My FANTASTIC FAN is installed in factory pre-drilled 14x14 inch hole in the bedroom ceiling put there by the manf for an optional second air conditioner. My fan is operated from 12VDC and picks up this voltage thru a couple of wires run thru the ceiling and taps into the 12VDC wiring for bedroom lights. My fantastic fan roof lid is cranked up and down from the inside and can be opened just a small amount to keep rain from coming in. Installing this yourself is not really hard but may overwhelm folks not used to doing things like this. Might be a good thing to have the RV folks to install it for you.
You can also purchase one of the twin window fan units from Lowes and adapt it to a trailer window in the bedroom and do the same thing putting this fan on exhaust mode (Blowing out) and allow fresh cool air to pulled in from opened windows on the other end of the trailer.
In the early days of air conditioning this was the way many home were setup with what called swamp coolers which was setup on the house roofs and pulled outside cool air into the unit and forced all of this cool air out a couple of windows on the other side of the house. They had water flowing over wooded slats to cool the incoming air. This was a closed water system that pooled in the bottom of the swamp cooler and pumped up thru the wooded slats vanes. Our house in Tempe AZ was setup this was back in the 60s and 70s.. Pulling or pushing cool outside fresh air has been around for years. You can still today purchase an RV SWAMP COOLER type roof mounted air conditioner that works like gang busters in the very dry climates with low humidity.
The early people of the great southwest would so the same thing by mounting a sheet type material down over their tent windows and keep them moist with water to help cool the air coming into the tents.
Hope this helps somewhat with your additional questions.
Roy Ken
