Regarding Portable AC units
Get one with an inlet and exhaust duct that you can put in your window. The exhaust vent hose must be insulated. It gets really hot and will defeat the purpose of the AC. You can buy insulated ducts from any hardware store.
Also regarding the inlet duct. The unit uses room air to cool the condenser then vents this out the exhaust duct. This air has to come from from somewhere. It comes in from outside via cracks and gaps in your RV shell. This air is warm and humid. Again defeating the purpose of your AC. Having an inlet duct vent draws the outside air in, through the condenser and back out the exhaust vent. No added heat to your room. The interior room air passes over the cooling coils (evaporator) and back into your room to cool it.
Mine does not have an inlet duct so I made one to attach to the intake side of the heat exchanger (condenser). Both the inlet and exhaust ducts are mounted to the window. Inlet on bottom, exhaust on top (heat rises). Try to direct the exhaust away from the intake.
Excellent review of portable AC units
https://youtu.be/_-mBeYC2KGc