Yes, that is exactly what you need to do, and yes, measure the voltage across the light bulb, from ground to neutral.
Hopefully this adventure will be helpful to others as well. It's educational for me, for sure.
I got the bulb hooked up and it doesn't light up. There's some voltage reading across it, the volt meter jiggles around a bit but stays under 5. So it's not enough to light anything up.
With the bulb plugged in, line to ground reads 124 or so.
Without the bulb plugged, the ESP surge protector won't transmit current. With the bulb plugged in, it does. Presumably, the voltage on the neutral triggers something in the ESP and shuts it down.
So bonding the neutral does indeed straighten out the signal generation. The oscilloscope shows a much better looking signal than before. And it's filterable. Running it through the ESP gives a perfect looking signal that's actually better than the utility mains.
Editing to add pictures:
For reference, this is a sample of the unbonded voltage output with no load.
Ugly nastiness. Nothing lines up. In the picture above, the scope settings are correct so it gives the correct voltages.
It doesn't get much better when you plug in a normal tool or load. At least they're more synchronized, but it still can't be good for tools or electronics:
But go ahead and bond earth-neutral, and voila!
Still a little fuzzy at the peaks, but not bad.
Let's zoom in on a peak.
What do you guys think? Good enough? I noticed the scope wasn't sure how to count the hertz, ended up counting all the little harmonics(?) to come up with 129Hz. But we're zoomed in pretty far here.
However, I have ESP power conditioners. Here's what comes through when you plug that into the bonded generator.
That's perfect, even if we did lose a couple volts.
Pretty smooth now:
Compared to utility power:
So it's probably very possible to set up two generators as the OP originally suggested, as long as the wiring and grounding can handle the completely unbalanced load.
My last question would be in the construction of a grounding plug. Is it better to wire up a dead short between the neutral and ground to bond the generator, or better to wire in a resistor in place of the incandescent bulb?