I have a 5500 watt portable generator. I then installed a “dryer” plug receptacle in the wall below the electrical box in the garage, and wired it to the dryer circuit breaker. Now when I lose commercial power, I turn off the feed from the power company and connect the generator to the circuit box. While I can’t run everything at once, I can selectively run essential services. I don’t run 220 volt appliances, but I could pick and choose if needed. PROBABLY NOT CODE, but it works for me.
I needed a welding circuit in the garage so I put in a sixty amp plug and breaker much more than needed but it matched the cable. I use it for the air compressor and the welder. To feed the system I make sure the Panel main breaker is OFF prior to starting the generator. The main breaker OFF precludes power going outside the house. I can either use my 5500 or the Honda 2000 and select the appropriate breakers. Sounds like we have pretty much the identical system.
I do the same thing. If you open the main there is no problem.