Make emmigration push scale larger as overcrowding increases. Right now, you get a 50 emmigration push from overcrowding, and it seems to be the same whether you're short 1 housing or 10. The effects on stability scale, and the emmigration push from unemployment scales, so emmigration from overcrowdedness should, too. It also gives egalitarians a way to keep a planet around a certain population level while still redirecting spare growth elsewhere instead of suppressing growth. Honestly, it should be balanced such that you shouldn't end up with much more than 5-10 overcrowdedness based on pop growth speeds, since going above that increases push so much that pops on the planet emmigrating actually decline back to less overcrowdedness.
Or at least, give us a policy/decision that lets us encourage emmigration without also removing growth. When I want all my various colonies to have their excess growth move to my massive ringworlds with plenty of jobs and space, I don't want to lose a bunch of that growth just to keep from needing to manually resettle.
