Welcome to the forum!!
Generator...........consider many watts you plan to consume (a 13,500 BTU AC's draws 1000 -1300 watts), hours per day, whether you will use a soft start to minimize starting AC watts, fuel consumption and fuel storage requirements. A Predetor 3500 inverter generator
https://generatorswift.com/predator-...ter-generator/ would be good size if you have a soft start AC.
Back up ecoflow system..........looks like a interesting option.
Lithium-ion batteries..........great option for boondocking, albeit pricy.
https://rvlifestyle.com/best-rv-batt...r-boondocking/
Do you really plan to boondock? By the time you invest in all of these you could purchase a camping club membership and stay for free with hook-ups and amenities (pool, spa, laundry, gated, wifi, cable tv, children play area, activities, etc.)