Switch refer and water heater to propane and only run the converter if it doesn't trip a breaker. Power management will be necessary. After the air conditioner gets started up you can usually turn on the converter with a problem. Also if power is supplied by central generator with temporary distribution system keep an eye on the voltage. Those temporary setups are famous for long and undersized extensions causing low voltage which will increase the current draw.
My 15K a/c draws 6-7 amps when running on 118 volts. I've measured it before.