Another option would be a Mini split system.
Small 115 volt units can oeer as much as about 12,000 btuh of cooling, and mounted on either the tongue or rear bumper of a trailer.
a small hole in a wall to allow freon lines in and out without needing the large 14x14 hole for a rooftop unit. You could even make a box to provide power to only this unit from the campsite pedestal using the 20 amp outlet so as not to eliminate the 30 amp your plugged into.
Home depot modelsOther website offer these type units as well some for lower cost.
The little Pioneer 9000 btuh model claims a 19.5 seer and specs claim a normal operating power usage of 680 watts, and 1100 max, which should allow it to run easily on a single 2000 watt generator as well.