Reaching Level 30 on Impossible?

[Helios]

Yes, I've tried a 30% Exp bonus from very early in the game, and even with 5% of Keeper of the Light's bonus, I still fell over 400,000 experience short of 31.

Making sure you get that level 30 leadership choice is huge. Leadership seems to be by far the most important statistic for any class. Whichever choice gives you the most end leadership is the best route to go.