Surgical Reclamation

• Loads up last Roman campaign
  
• Finish Blitzing the Vandals before the 1st chapter ends
  
• Ostrogoths still haven't declared war on me so I start things off by attacking Sicily
  
• In declare war screen
  
• Notice the call allies button
  
• Let'sExperiment.EXE
  
• Don't call in the Roman Empire
  
• Goths rarely ever chase me into reclaimed territory even if I only have one army
  
• Moors invade
  
• Play for a few minutes
  
• Check map and Moors are almost completely destroyed
  
• O_o Wut?
  
• Almost all the Roman armies are down there or surpressing rebels in Italy

Long story short if you don't want to have to deal with the deathstack invasions or rebel surpression, pre-emptively declare war on your enemies and don't call in the Romans.
As long as they don't eventually wind up declaring war on your target too (which they never really did in my test run) They just surpress rebels and respond to invasions.

NOTE: When the langobards showed up they gave a half assed defense but they still at least tried. They kept those 6 full stacks in their core territory because I guess they just never leave. Still, you can pretty much wipe the rest of the map and replenish in friendly territory before moving in to eliminate whatevers left.

Now moving in without ANY help can be tricky to manage. Mostly I just used spawn armies until the free payment on them ran out and then deleted all the units and parked the generals on sicily. This way they're safe and out of danger whilst still technically growing as camps, providing money (and potentially research). Pump all of your money into a highly elite and expensive army for belisaurius, going for a carpenter as quickly as you can to get siege equipment so you don't have to wait a turn or more during city attacks. Smash and grab, use agents to slow down approaching armies and avoid confrontation whenever possible. Eventually, even with the cheating AI's extra money, their strength will trickle down and you can clean them off the map. Usually don't go out of your way to deal with rebels, but if they're on the path might as well nip them in the bud. When you have enough funds retrofit another army from one of your parked generals and move either in unison or, if you want to be risky, at opposite ends to divide the enemy (hopefully).

Hope this helps!