Would it be possible to index the subsidy to factors presumaby relevant to the cash the AI "should" be receiving?

Three examples, bearing in mind that I have no idea what I'm talking about:

1. Different amounts for each level settlement -- 500 for a town, 750 for a small town, and so on.

2. Certain amounts for each level of market and for each level of port, probably in addition to a base per-settlement subsidy.

3. Some multiple of the income actually produced by a faction's settlements.

If any of these are technically possible, I'd be more than glad to run some gameplay tests to see how they play out.