Some have indicated that the air conditioner will run on one Yamaha 2400. I am sure someone that has experience with Yamaha's will provide further info.
If you decide to buy the Honda 2000, you will probably need two generators. However, if you camp at 7,000 feet, you may not need the air conditioner; in which case, one unit would suffice.
Personally, I'd buy the "Companion" with the RV type connector. That unit costs a little more, but the inverter is higher capacity and designed for parallel operation (connecting two Honda 2000's together) for more power and to run the air conditioner. If you only buy one, the Companion will have the RV connector that is compatible with the OEM shore power cable, via an inexpensive adapter plug. Note: This plug usually comes with the (optional) parallel kit for joining two generators, or you can purchase one separately for a couple of dollars.
Then, if you decide that you need the air conditioner, you can purchase the second Honda 2000 (with standard 110 outlets), at a later date. If you camp mostly in the spring and fall, and above 5,000 feet in the summer, you may not need the second generator.
We purchased and carry both, but use only one most of the time, as we rarely camp where an air conditioner is needed. The second generator is a backup, which we sometimes share with a neighbor when group camping.