I do something like that, but a little bigger, and it works great. I put it together after a two-week outage a few years ago (we get multi-day outages almost ev

I do something like that, but a little bigger, and it works great. I put it together after a two-week outage a few years ago (we get multi-day outages almost every year). I have two Bluetti AC300s and four B300 batteries. That gives me ~12 KWh (~24 hours for us) and 240 V so that it can feed the entire house. The buffer thing you mentioned is key... our average usage is around 400 W, so the generator can be pretty small and the battery system will handle the peaks. We have a hand carryable 2 KW inverter generator. The challenge with this system is that you need 240 V to charge the two Bluetti units (or two 120 V lines on opposite legs of a 240 V feed to ensure the proper phase relationship). I got around this by buying three Mean Well 48 VDC power supplies (meant for large LED installations). Each will do ~500 W. I plug them into the Bluetti units as if they were solar panels. Running the generator through them for 6-8 hours a day is enough to keep the batteries going indefinitely. That's 2-3 gallons of gas per day. And the first day of an outage requires no gas. In the summer, we have a handful of solar panels I put up in the yard to keep the batteries topped up when not being used for outages (our outages are mostly wind+snow events in winter). Our evaporative cooler, chest freezer, and washer / dryer run off the batteries while the panels are up.