technically if there was a subfaction scrip every region could eventually get their own private budget to spend and only after every region had spent it´s own cash would the remanents be used to develop an economic building in any given region

another solution could perhaps be to implement 55 gold mines in the sahara and since it´s unconquerable the rebel factions would always have a semblance of an economy balance and maybe coup that with a 0 deficit script(meaning the rebels would never go into debt )