Just avoid the main enemy army. Cap one of their territories if they settle down to siege one of yours. If you can keep trading approximately 1 for 1 then maybe you can eventually get some kind of a peace, even becoming a vassal because it's still fairly easy to expand as a vassal. This is what I've had most success with.
Try to use Ninjas on his Honor as everyone's is low at game start, although there's not much chance of getting a ninja clan offer with so few provinces. I didn't have much luck with attempted Plots, either.
I've mostly started the original earlier scenario with Mori. Even though it's a one-province vassal, it's an easier start, and breaking away from your clan is made easier due to the map location situation.
Try to use Ninjas on his Honor as everyone's is low at game start, although there's not much chance of getting a ninja clan offer with so few provinces. I didn't have much luck with attempted Plots, either.
I've mostly started the original earlier scenario with Mori. Even though it's a one-province vassal, it's an easier start, and breaking away from your clan is made easier due to the map location situation.