Assuming your local AHJ allows such setup, conceptually that should work but you will probably need to also keep Envoy off to avoid potential issues.

I smell smoke looking at putting those 3 modules in series but parallel with the inverters

My understanding is that iQ7 has floating DC stage so it should be OK but the wiring will now see high DC voltage referenced to ground and that's one reason why I mentioned AHJ allowance for such setup. I doubt Enphase ever tested such setup.

IMO using a separate set of panels for a backup power source like the Solar Generator would be a better decision instead of doing something to your existing solar system. But I can understand the a lot of people don.t like the idea of not being able to use their solar pv equipment when the grid is down.

What I think most people don't understand is that a small 1000watt solar generator will really not power much load for a long time. So if emergency power is required for your loads then maybe look into a real generator that has dual fuel capabilities.

Panels - likely not. PV panels are pretty rugged and don't much care about potentials (as long as you don't exceed their voltage rating, which is usually 600 or 1000 volts.)
Inverters - possibly. They are designed to operate isolated from each other; this would be forcing a galvanic reference on them that they are not expecting.
They will "know" because the panel on the right will see its ground (referenced to the imaginary neutral between the two hot lines going to that inverter) at around ground. The panel on the right will see that ground at 80 volts above the neutral. IF all the inverters have isolation that is good to a few hundred volts (which is likely) AND the control software doesn't check that the voltage levels are what it expects to see (which might be true) then it will work.

One of the reasons I would be hesitant is that inverters aren't designed for this. For a consumer electronics device, like your cellphone charger, then isolation is a life safety feature, and will almost be guaranteed to be excellent. But for these panels, there's no requirement for that, as long as the panels shut down cleanly and completely when the power goes away.

To do something safer, you could use a 220 volt DPDT relay at each junction box. When power is applied to the array, the relays are closed, and the inverter is connected. When the power is removed, the relays fall open, and the series connection is made and the power is available at the end of the extra wires.