> there's no way i'm letting the AI spend my money for me

You do not have to let the AI spend your money. Just make sure that a
governor comes by every so often and leaves a list of what needs to be done.
In my France campaign I have about 25 provinces in France proper. I have
two active builders commissioning most construction and one hypohondriac
with an elite cavalry stack taking care of rebels. I seldom leave a city idle,
and when I do it is usually because an inquisitor wanders in.

My seven provinces in the Holy Lands are a pain, because I have had at most
three generals there at one time. Two are campaigning respectively against
the Moors and the Turk/Bisantium alliance(!) and the other one runs around
like crazy, trying to keep Jerusalem, Cairo, Alexandria, etc. happy.