Cracking,
It's one of my favorite forms of fortification to build.(actually have a series of round house's and oppidium on a commissions wish list to do for the beginning of next year. So I'll enjoy watching your progress.)
Will you add an area of vitrification to the wall as a variation in detailing ? Or build an optional embankment and ditch to sit the whole thing on. So you can go full hillfort as and when the mood takes you?