The small windows are no problem with ventilation, especially if you open the roof vent. In addition, you should consider getting some mosquito netting and placing it over the cab windows and then rolling the window down plus get netting for the rear window (if it opens) to provide additional ventilation. And then you can always hang netting across the side door opening to provide ventilation w/o mosquitos and flies. There have been many responses over the past few years on screening and other options for getting good ventilation. Using screening on the PW or RT is much less expensive than replacing windows. Having the ceiling vent fan on, or at least opening the vent helps a lot with pulling cool air into the RV from outside.