If you don't mind the risk I suppose you could create a stack, stick'em on a ship, and head off. Basically relo'ing your home base to one of the nanban provinces.
The one catch of course with Oda, you'll have to get free of your master first or you won't be in a position to declare war, and therefore couldn't land your troops.
This isn't really so much an Oda campaign at this point if you pursue this strategy, but that's not to say I've not done it. When I get super annoyed with my location circumstances, often something that comes up when I'm somewhere in the middle of the map, I've been known to open up a 2nd front for insurance in case things really hit the fan.
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