My observation has been that it takes more power to start an AC unit than it does to run it. If you can start the AC units separately, 4500 watts might be able to start a second unit after the first one has been running. Then you could at least cool your trailer down before they start cycling together. I only have one AC. It has ducts, but most of the cool air is blown directly beneath it into the living space, while the "bedroom" stays warm. I have found that a turbo fan pointed up and out from the back of the sleeping area can blow the hottest air near the ceiling out while pulling in cooler air that lays a little lower. And a little air movement can make warmer temperatures more comfortable. This might help in the short term. Good luck with your generator search.
JRMunn