Money is always incredibly tight, much more so than the other resources... You have to pay your soldiers, the Futamazons and incredibly expensive new buildings. It's so tight I usually have nothing left over to increase my charisma and intelligence. It's also incredibly awkward if you ruin your income by hiring a new soldier and suddenly it would take ages to research and/or build the next money-making building.... so you usually have to fire the soldier again. So you really can't have many of your "modern" troops at the moment.
Oh, one probable exploit I found: When the Futamazons increase their fee, you can stop paying and start paying again via diplomacy... at the previous cost, I think. Until they want to raise the fees again. Rinse. Repeat. Never gets more expensive. And I still didn't have comfortable amounts of money...
A field/map/out-of-town-building that produces gold could be good...
Speaking of field-buildings: Can you add manually building outposts at some point? Because as it is, there's no point to expand past your 5x5 corner except to grab special sites... and trade outposts offer much needed gold. Or, in combination with the gold-producing field-buildings mentioned above: Lessen the flat bonuses on outposts and indeed make them boost certain productivities of the buildings around them. E.g. a trade outpost boosts gold-production of nearby buildings. Kinda like windmills, just limited locally (which could be a good idea for windmills, actually).
To avoid the previous mindless map-filling... limit outpost numbers somehow? Either a hard-cap on their number, or increasing costs. The conquered capitals would be bonus ones that don't increase costs/take up a slot(or come with a free bonus slot)...
Just brainstorming here
