I have the goods, coins are the bottleneck.
Well, you did say it was an experimental city, so you're gonna have to, you know...
I don't know of any magic setup that's going to generate millions fast (if I did I'd be on my yacht right now, instead of my couch). I think St Marks + Chateau is your best bet. Just don't do the UBQ. Don't forget about the CF's coins -- one of mine produces well over 100k a day (L22 or so?). And grab any special buildings you can get that have good coin production.
So, why scout all the provinces through FE? What's the attraction?