I have a portable 9500/12500DF gen that we run on propane. (we try not to use gas in our gen if at all possible) I have a 50amp inlet box next to the main box. A 15ft 50amp gen cord goes from my generator into the inlet box. The gen sits in a gen house i built for it. Our generator gets moved to the main box when needed. Our gen sits in the garage, gets moved into the gen house when needed. I also installed a "MAIN/GEN breaker lockout", that way there is no way i`m feeding power back to the main street line. An 8ft grounding rod installed to hook the gen to for grounding for unbonded neutral on the generator. Used it several times since last year, works very well. Keeps the fridge, garage freezer, house furnace, heat tape for the water lines, well pump, a few lights in the house. All good here.
Pay very close attention to "Bonded vs Unbonded" with portable generators! It matters!