So, avoid the Saints Book, and just concentrate on buying properties or doing Activities if you really want to add to your controlled hoods.
However, because Steelport is under martial law from here on out - which means that STAG is absolutely everywhere and you're almost always under at least one-star notoriety with the cops - it'll be unnecessarily dangerous and complicated to do any diversions. If you have Activities you haven't done yet, or you still have neighborhoods to take over, now would be a good time to do it so you keep the cash rolling in. You're almost done with the campaign of Saints Row: The Third, and STAG's invasion of Steelport can't go without resistance.