rebels- your greatest allies

Hi everyone. been watching the forums but new to posting. playing second game at VH/VH. byzantian empire. own to N italy and most of turks and all ex hungary.
am at war with turks, venice, mongols, papal states, milan, russia, poland.
my main problem was finance. keeping a large enough army to fight off all above and keep up building works. so... must expand and get sack money but can't afford huge garrisons in areas not my religion.
my solution is to maintain my new border towns flock in priests and slowly expand as before. however the one differance is that i have two half stacks on a fund-raising tour. they have gone around my enemies front line and are happily attacking their undefended heartland. sacking cities selling all buildings and leaving again for the next undefended city/castle.
this has multiple advantages.
1. the AI is following my fast raiders around instead of attacking my empire.
2. rebels quickly take the newly denuded towns with 3/4 stack of rebels making them hard for ai to recapture and not worth it when they do.
3. mongols are striuggling against me and rebels as all ex-turkish land heavily defended by rebels and no unit making buildings when they do take.
4. this all takes place in areas i never want to hold (milans holdings in france and poland at the moment so no long term cost to me.) between this and my regular expansion i am taking a city a turn but only keeping a new city every 4 turns or so.
5. starting to notice lowered quality troops from states that have foolishly taken these rebel towns. ha ha ha.

For those areas that you do want to retain for future expansion and a strategic position, it's useful if possible to turn them into castles from cities until you have the troops necessary to garrison them, or have converted the population to your religion, particularly if the province is far from your capital. Ideally the settlement has not yet reached the point where it can no longer be converted to a castle.

Castles have a much less Distance to capital penalty, as well as much less religious unrest penalty than cities. In addition, castles can be used to retrain and recruit units for a prolonged war.

thanks sbroadbent.
this though is just a money raising, faction weakening/distracting strategy. if i intend to keep a province i move in my preachers and garrison heavily until my frontline moves on. i have almost destroyed poland with one half stack. they did have 8 provinces and now have two. only 2 provinces left now. i have occupied none and will not ever. certainly not until all italy fallen and then only to get province number for victory. however my frontline with this area is very peaceful now they are all rebel and my building program continues well even though my non conquest free expenditiure is only 9000 per turn i am able to spend 15000-25000 per turn on building through this strategy

There's both a good and bad aspect to point out about converting all sacked settlements into cities, though the good arguably outweigh the bad by a bit. The good is that it makes it easier to capture later on in terms of troop quality and wall strength, and cities generally produce better cashflow. The bad part is that is also makes it easier for the AI to capture them (in theory at least), and when they finally do recapture they now have a better source of income. It's still debated whether or not the AI actually benefits from a higher income, but it's still something to consider.

Cheers!