On a normal single phase residential installation, shutting off the main breaker does NOT disconnect the neutral or the ground conductors, only the power conductors . Most should have two 120V hot leads and the main breaker only disconnects those two cables coming from the meter box into your main panel box.
You don't need to satisfy anyone on this OWF site of your installation of a generator, you must satisfy the requirements of your local utility provider! Regardless of whether you have codes or not where you live, if you are not sure of the requirements at your location, you should contact them before potentially backfeeding into their system. If they are reputible, they have a policy/procedure for this. Most will disconnect the commericial side when they find a generator not installed correctly and won't turn commercial power back on until the generator install is corrected.
God forbid, if one of their employees gets hurt or killed, and they trace it back to someone backfeeding into their system, I would not want to be that person! There are wayyyy too many lawyers and the utility company usually has many good ones that will make it their mission to find someone else responsible for something like this other than their client!