That was an H/H campaign, but should work fine on VH/VH.

My next campaign I used basically the same strategy on VH/VH with the Vandals settling in Rome/Tarentum/Ravenna and in worked like a charm.

I relentlessly pounded the WRE and the greek part of the ERE while in horde mode, until I settled with around 250,000 cash and lots of rebel grey where the romans used to be. In the west, you will get more competition from other hordes and factions. The goths plopped down right next to me in Mediolanum, which I would have liked to own, but elected to coexist instead. The Alemanni and the Franks took advantage of the swath I had cleared and soon showed up on by borders.

With the Vandals, you have the advantage you only need 10 settlements though. I never even had an economy, just used my horde money to pump out enough units to take the cities I needed and a few more.