We chose the A/C and, with some 40K miles on the trailer, have used it quite a few times on our cross-country jaunts. You should be aware, however, that these are room air-conditioners, and we've now replaced ours twice. The vibration of many miles, along with some wash-board excursions eventually fatigued the soldered parts, and most aren't repairable. Some A/C models seem to have compressors less free to move, and probably will last much longer. The newest one seems much tighter than the last.
The good news, especially for those of you with the new hinge on the hatch, is that it's not a bad do-it-yourself replacement. The expensive part was the original trailer mods to fit the A/C. You can find similar window units for a reasonable price. Even though our trailer has the old-style hinge, I removed the hatch and installed quick-connects on the wiring. With care, I managed the job without compromising the hatch seal. Just remember to measure carefully, as the A/C units vary in size quite a bit.
Later,
Skip Eastman