It is most likely alignment. Your description sounded exactly like our issue right down to the passenger side tire being more worn on the outside.
We just had our truck alignment adjusted to allow for the shift in weight caused by the camper. The guy who did the work explained it all very carefully and hopefully fixed the problem. We will find out as we are about to leave on a trip. He told me to come back when we returned from the trip and he would re-check the tire wear patterns to see if all was as it should be.
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