When I had my 5th wheel, the front a/c was a Penguin 13500 and not controlled by the main living area thermostat but had manual controls. If I ran it on max continuously, it would frost up and start dripping on the mattress. Solution was to run it a little less than max so that it cycled more often.
Also, if you are going to tighten bolts, don't get too aggressive with them and tighten them a little at a time going from corner to corner. Doubt that the gasket is your problem though.
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