A single 30 amp two pole breaker, would indicate the generator is wired for 230v output and 6900VA aka Watts
The problem with this is that over loading only one side trips the breaker and kills power to everything in the house
Also a 230v system should have the loads evenly distributed between both legs
Not wired like smaller RV generators with a dedicated 20 amp circuit for one a/c
Have you put the fridge and the water heater on propane, not on auto mode or electric
What is the condition of your batteries, If they are drawing a heavy charge, that adds to the load on the generator
On hot days like today 102°F
I try to start early charge the batteries before running the A/C
Then try to get the A/C going before it's 90° + inside
And try running only one for awhile, don't start both only minutes apart
They are working the hardest when they first startup
Two starting up one after the other will be a very heavy load