Hi Mary - I'll give you my thoughts but others may well have much better advice.
I THINK your AC would run with a generator that has 2500 Watts peak output, but, if other things are on in the trailer too, you'd be better off with two, 2000 Watt units. The problem is that the starting electrical pull of the AC is quite high, generally more than 2000 Watts, but the running Wattage is lower. If you have other things, such as the lights, maybe the refrigerator, the hot water heater and possibly a microwave on when the AC starts, it may pull more than 2500 Watts. They have "pairing" cables that you use to connect two generators together to double their output. If you don't want to use two generators, a 3000 Watt unit would probably be fine.
Whatever you do, get an inverter generator that is QUIET! We've been at some campgrounds where a neighbor runs a generator that sounds like a jet engine. This is very unpleasant, and rude to your fellow campers as you can imagine. Units from Honda and those you might find in Home Depot or Costco are good in this respect. Look for ones that have a noise level less than 65 db. My Honda has a sound output that is equivalent to human conversation, but it is only a 1000 Watt unit.
Hi-Lo 1707T - Tire Minder TPMS on Tow Vehicle and Trailer, 300W Solar Battery Charger, Equal-i-zer WDH
2014 F150 Platinum 4x4 3.5L EcoBoost SCrew