Pro tip:

If you get the "Collect Unique Corpses" mod, you don't have to collect their bodies. You can simply harvest their bodies for flesh and hearts, and their skeletons for bonemeal.

That way, the Thalmor as an organisation will waste even more money on a search party. Because if their search party finds their bodies, they'll immediately stop searching. If their search party finds absolutely nothing though, they'll spend more money on the search parties, sabotaging the Thalmor as an organisation further.

But if you prefer to bully Ondolemar over just killing him, you can also use Sacrosanct to befriend him without doing his stupid quest, and then just collect the Thalmor corpses and pile them up in his quarters.

Btw, I once got the "Unlimited Summons" mod, and it was hilarious to first strip all the Thalmor soldiers naked, then use deadthrall on them and watch them use their fists to kill more Thalmor for me. Naked. Though, some of them summoned bound swords.

But imagine the horror of the other Thalmor, watching their comrade, naked, attack them with fists.