I am full of ideas in this festive period apperently.
Anyway so a big issue with PVP is that the map is huge but the armies pretty only fight over the inner keeps, Bridge and the Chalman and Nikel gates. There is just no reason to leave that battle zone when its ineffienct for all the riding required to travel out of your way. At least when solo, I know organised groups can use that space but the zergs have no reason.
Now the idea of making more capturable towns has the issue that the AD zone doesn't have a nice capturable town nearby like Cheydinhal.
So instead I suggest having moving supply trains as a capturable resource, they would avoid the worst of the fighting and travel through some of these blank zones. They act in a smilar way to payload quests in things like TF2 and Overwatch. You can capture or defend these supply trains for your alliances advantage. You will try to get them safely to your keeps for AP.
If no one fights for them they will just give passive team AP, like resources.
Cryodil is so big you can have lots of different types of PVP all with in the same map.