As to AC in a small trailer in the real South, anything else is not really and option I care to think about.
Besides the heat there is the unrelenting humidity, not to mention the bugs.
I am happy with the mini-split as to weight
and noise factor.
A window unit could be made to work as well, but anything worth doing is worth overdoing as well...
Also the heat pump means that the heater (for hookups) is taken care of as well.
We use our camper for travel and as a mobile motel room that we don't have to carry luggage up to every night.