How to avoid these full stack campaigns...

[Titus Marcellus Scato]

Me too.

To make things fun on M/M, with many factions, you can afford to hire a mercenary general and a full stack of mercs and go interfere in the affairs of other empires, either to turn events back into a more historical course or to throw a spanner in the works of a strong power. This is great fun, and allows you to use up your extra money, and fight battles with troops that wouldn't normally be recruitable by your faction. On M/M, the AI doesn't hire very many mercs, so most of them are available for the human player to buy.

So as Ptolemies you could raise a merc stack in Greece to represent the Aetolian League, for example, or maybe Pergamon, and mess up the Macedonian conquest of Greece. Koinon Hellenon can raise a stack to fight in Sicily. Carthage could raise a stack to set up Tyre and Bostra as a buffer zone between the Ptolemies and Seleucids, or set up an Irish enclave in the British Isles to fight the Casse. There's lots of opportunities for Rome to interfere virtually everywhere.

At the moment I'm playing Saba on M/M, and I used Force Diplomacy to force Carthage to give me Kirtan and Gabene, which I now run as a Numidian 'sub-faction'. It plays havoc with my economy as the Numidian cities are corrupt as hell, but it's great fun playing as the Numidians, even when the Carthaginians squash me like a bug!