1. ToB spoilers should really be flagged in the SoA forum.
2. You CANNOT legally get to lvl20/20 in plain SoA even completing the whole game (a single class mage can only get lvl17)
3. Although some mods may prove uncomfortably challenging if you are not very high level, 15/14 seems strong enough for me to even beat the final boss (in plain SoA that is

)