fatsweets: You can avoid losing money to your "protector" simply by spending it. Construct buildings and train units untill you have almost nothing left before hitting the End Turn button. You won't be able to save up a big treasury, but on the other hand you get to build up your infrastructure and army for the few turns that the peace lasts, which will leave you in stronger position to face the inevitable return to hostilities.

Maion Maroneios: I would recommend that instead of trying to hold on to the cities you sacked, give (or better yet, sell) them to the Ptolemaioi/Seleukides, which ever of the two is doing worse at the time being. This way you can maintain the balance of power between them, keeping them at each other's throats and too busy to expand in your direction. All the while you fatten your treasury with the spoils of war.