Jim
My "portable" generator has multiple outlets, of differing voltages, and amperage ratings. I have a Generac GP-17.5KW, generator.
I have a 240/50amp, 240/30 amp. 120/20 amps, both GFCI protected, and not, at the generator, and 12vdc.
A person running a portable generator, whether back feeding, or not, really needs to understand the grounding. Probably, at most, there will be problems with GFCI protected circuits, but,,,,
Lots of "newish" NEC codes, and OSHA requirements, have happened in the last decade. If you're going to run a portable generator, be damn careful, or break down and hire an electrician to install all the correct electrical equipment. Or, do as you have done, and install a permanent standby unit.
Off the soap box for now.