If you are getting an 18 to 20 degF temp difference between the inlet and outlet ait on the unit on high fan, that is about all it will do.
They units are hermetic and there are no charge ing ports. Remember that the bedroom area is a much smaller area than the front part of the coach. The front of the coach also has a lot more glass for a heat gain.
Try putting a small fan on the floor in the bedroom to blow air to the front. Also, cover all of the windshield area with a solar covering on the outside of the coach. Inside covers still have the heat inside the conditioned space.
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