Reaching Level 30 on Impossible?

[Helios]

I've played through a few times, but I've never had a character reach level 30 on Impossible difficulty. On my current game, my first as a Paladin, I still don't think I'm going to make it, since I'm level 18 after finishing the Dwarf Treaty quest and I've been fighting every enemy. I have two levels of learning (very early on) and am using the mod for "The Next Generation" and Rina had the baby that gives 20% experience, and one level of Keeper of the Light. Do I need to equip the Tactics Treatise and Bloody Tape very early on, too, for that extra boost of EXP to make it to 30? Can Mages or Warriors even make it to 30 without KotL?

Or am I receiving some penalty to battle EXP since with my characters I always take leadership at level up, no matter what. Thus the mobs on Impossible only scout the groups as "Strong" or "Very Strong". But I've read the translated fan manual pages on battle EXP and it doesn't mention anything about your own army influencing EXP.

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Edit: OK, it looks like I went overboard with EXP boosting in this playthrough, as I'm already level 24 with 7 locations still left to clear before the final battle. And obviously per my question, in-game EXP will vary for each playthrough given the somewhat randomness of the encounters, but does anyone have an idea of a rough plan for reaching level 30 without wasting too many runes (and equipment slots) to reach level 30? I'm a bit of a power-gamer who doesn't want to waste my runes on future playthroughs. Would getting only 3 levels of Learning be roughly enough to reach level 30 on Impossible?