Mystery plug on Honda Generator
Might ruffle some feathers here but...
You really don't need a transfer switch.
Simply turn off the main breaker.
Wire the generator to an appropriately sized 2 pole 240 breaker.
Mind your amperage and turn off central AC, range, etc.
Probably OK to cycle the water heater if everything else is off.
Unless you have big draws on the 15 and 20A circuits, you can probably leave those on.
Again, mind your amperage and startup current.
Room light circuits should eb OK to leave on but I wouldn't have all the lights on at the same time.
Probably OK to run a couple fans or a window unit AC.
I've got an "AmProbe" from my days as an electrician's apprentice and I use that to check the draw on each leg of the breaker feeding the panel from the generator.
Balancing the load is a good idea, as well.