I decided to mess around with Nagaoka just on normal difficulty to see how much of an income I could get in a year. It just doesn't work like S2 does but it's probably more realistic?. I looted 2 provinces, sold military access to anyone that I could, purposely killed my daimyo and 1 general and scuppered my navy to cut costs. At about the year point I've run out of things to build due to the techs taking a while to learn. I got up to the third level of modernisation. Basically the shogunates control the right of the map and imperials control the left. Obviously this wouldn't work as well at higher difficulties but it's good to know the possibilities.
I had to try it just for fun.