Thanks all for your pieces of advice.
Moats and trenches are out of question, I've seen proud screenshots of them and I find them horrendous. And if I find farming wood to spawnproof to be anti-fun, I can let you imagine what I think about farming wood AND stone :D
Mods are out of question for me too, mostly on an early access game for obvious reasons. For now I see stakewalls as the only solution for now (I hope non-raid mobs don't attack them too), but I really hope devs bring back the old spawning mechanism. I didn't have this problem in earlier versions of the game (or to such a lesser extent that I don't remember it)