[bestgenman]

This is just a guess since I’m not very familiar with Outback inverters.  It sounds as if the problem is frequency related, works fine on shore where it sees 60hz.  It also seems to work with an AC unit on with generator running but when the AC is off it shuts down.  When the generator is unloaded the frequency is around 63hz but with an AC unit on the frequency drops to a level acceptable for the inverter.  

Does this sound like what is happening?