Run AC from inverter in truck?

Assuming the engine is running, at operating temp, the batteries should be fully charged. With the alternator propping up the battery voltage, and decent wires (whatever the inverter recommends) you should be able to start the AC. The auto batteries are designed for high cranking amps (which look the same as startup surge on an inverter). Runtime is another thing, as at idle you may be barely able to charge the batteries with the lights and trucks fan on - without the inverter in the picture. Most factory (even the upgraded ones) put 20-40% rated output at idle, less when hot. Aftermarket alternators (I like Mean Green) out put far more at idle, and if big enough can support the AC when running down the road.