Why would the total amount of wizards be important? With 70% guilds you need about 6 rl days to reach 4 wpa. Thats a worst case scenario. one question is, if you get chained at all. It might depend on your kingdom. If you have opa monster dryads and orcs and wpa moster dark elves in your kingdom, you might not be a priority. Especially since even chained you stay a dangerous attacker.
I see an undead-mystics mage role as a t/m supporter: mostly doing fireballs and max duration greeds against other attackers, casting rituals and denying enemy rituals.
You dont need a lot of wpa for this role.