It's also a dangerous situation. But like you, I often think about things and how equipment would react to unorthodox applications.
It's okay to think and wonder, but I would not ever consider doing this. Theoretically, it would work, provided the upstream load was very low, below output FLA of the genset. The genset breaker would protect the genset from overload, but would not survive restoration of utilty power while in operation.
Just curious? Do you know someone who is doing this, or plans to try it? I sure hope not
