What im looking for is a mod that adds new spells to the game, but only to be found as lootable spellbooks with low droprate. Is there any, or/and how hard would it be to add all spells from Phenderix & Midas to loot only? (i havent modded anything, yet)

Vanilla spells would still be found from vendors but all new spells you would have to find from enemies/chests. I think this would make skyrims loot much more interesting, and all mage-playthroughs different as you wouldnt know what new powerful spells you find each time.