UPDATE: The electrician finally squeezed me in and got the generator connected to the house. My underground conduit came out in the right spot next to the house by good fortune.
The generator lock-out wasn't what I was expecting at all - I thought it would be a black box of some sort (having never really thought about it at all) but it's just a mechanical lock that doesn't allow the two top left breakers, which is the generator input, from being in the ON position at the same time as the main breaker. It's effective.
Had him install a whole-house surge protector while he was in there. He did all the work with the power on the whole time
The moment of truth came, fired up the genset, flipped the main breaker OFF, generator breakers ON and .... nothing
Woops, forgot to close the contactor....
With the HVAC running and the normal amount of lights turned on (it was about 8:30pm when he finished) and all the other things that normally run, the load was about 25%. Turning on the only two-phase load, the oven, took it to about 75%. Without the oven and just lights, clothes dryer (gas so one-phase) and the whole-house ventilation fan it was about 40%.
That was just some ad-hoc testing, nothing detailed, and only to get a feel for whether the 802 was going to be enough generator. I'll do some more detailed testing later, but for now I'm confident I can power pretty much anything in the house during an outage as long as I'm mindful about the oven (which I very much doubt I'll need to run) and the washer/dryer running simultaneously.
Wife was pleasantly surprised at how quiet it was, and given the time of night and nothing running like TV or radio noise floor, was welcome news.
So, I'm glad I ended up with the 802 vs the 803. I suspect I'd need to purposefully turn on things I don't need just to keep the load sufficient to prevent wet stacking the motor with the 803, which would be drinking diesel at a much higher rate.
Only thing left is some better load testing and finding an external tank.