Thanks for replies everyone. It sounds like technically, the answer is yes, if the LRA start-up needs of an A.C. exceeded the powerwalls, but did not exceed the powerwalls + Solar (at that moment) then it should work. The caveats are: 1) if powerwalls are fully charged and have shut down solar production then the solar production would not be available. 2) Solar must be supplying an appropriate amount of power at that moment to the currently charging powerwalls. 3) Other household needs are not using most of that solar power being produced at that moment.
I ask the question because if its really hot out, your solar is producing all day long, to the point your powerwalls are full, but you couldn't run A.C., seems like a waste. Since long outages are fairly rare in my hood (unless PG&E starts hosing us with "safety" outages) then I have no problem with the need to actively manage/monitor the system for a window of opportunity to turn on the A.C. system.