From what I've read, JeremyC, is that it takes at LEAST a 2400W generator (at the surge rating) to run an AC (single) unit. If you have two as some bigger trailers do, then you would need at least twice that.
The main problem is at start-up, you need that much wattage to get the AC started - it doesn't require that much to run it once it gets going.
I have a popup with one AC unit and had a generator I used for college football tailgating (Honda EU2000i) with 2000W surge but now Honda has engineered more efficiency to the newer units of the same type (which are 2200W surge-Honda offers bigger units). That size, while great for tailgating, is just under what I needed for my popup AC. Not that I dry camp anyway.
So you can opt for the one-big-unit solution or the two smaller dual-connected units. Like Teamubr said, you need a lot of wattage (at a minimum the 4800W I show above or the 5500W he suggests). It just depends on what sizes are available to meet your needs.
Bama Ed
PS - if you're going to be camping around other folks, opt for the quieter Honda or Yamaha generators. They (along with others) make what I call "job site" generators which are NOT quiet and fine for a daytime work/job/construction site. They would be loud for any any neighbors around you if it had to run into the evening/night. So consider that because you might be on the receiving end of a loud generator from someone else.