We'll have a stewardship action available next turn, as we finished rebuilding one of the major cities, so we can use it to expand our farming income if necessary. Slight deficit doesn't mean any pf our population will be starving, though it will be close.
So I think that its worth it to take the most expensive option here, and get the Ettin King and all of his best fighters on our side for the fight against Hakkar. With their giant height and skin tougher than dragonskin (according to the wiki), they can be a key part of our attack on the Hakkari.
I see us using them either against fortifications, as a counter to any large/armored forces the hakkari have, or holding them back to use as a surprise blitzkrieg force against the enemy casters during a key battle. It all depends on what we see in the Hakkari lands, and what we need most.