3500W generator I picked up

Just my FYI- shutting off the “main” does not shut off the neutral. This allows for voltage back to the pole. And sometimes the main breaker does not disconnect both legs due to contacts sticking (rare cases but it happens) code calls for a mechanical disconnect like a knife switch. Even an automatic control panel has a spring loaded solenoid pull that disconnects the 3 legs. 4th leg (ground) goes to a grounding rod back to earth. Typically 6’ to 8’ long dependent on soil conditions. But hey- what do I know.

I'm not sure that neutral is an issue. The neutral is tied to ground at the pole and at the house. Most? All? houses around here only have a two wire plus ground feed. Many "drops" (like mine) even have a bare ground/ neutral. The neutral at the main box is grounded, and the neutral and transformer case is grounded at the pole

In my case I am sort of "double" protected. I have the main on the garage and it goes from there to the house box which has it's own "main" that disconnects from that line. So there are two "mains" in series so to say. I pull both of them and the garage is completely dead during genset work. On mine the genset feeds the house box