You are having issues with enthalpy. It completely changes with varying conditions. It isn't just humidity it's all conditions. The more even your temp and humidity is with outside the better off you are. Unless the trees are sweating opening the doors on the RV will help with the exception that your temp will drop. This is why insulation helps because it offsets those conditions. That is why opening a roof vent helps. I have no condensation in the mornings but the minute I get up, make coffee, turn up the heat, the windows condensate. However, enthalpy is brutal to control so at the end of the day you have to just deal with it or manage the best you can.
Happy trails!