In my last solo playthrough i had a longhouse in meadows without any defenses. I didn't even have doors on my building. The only problematic raids were troll raids. When they appear, i just go outside (far from the building) and roll dodge their hits until the raid is finished. When the raid is over, i kill them. I found this is the best way to fight them, because if you kill them earlier another will spawn.
It is also a good idea to build on small islands or peninsulas so the raid can come only from one side. Taming wolves early and placing them strategically around the base helps a lot too