Stone walls. Torches (or other no-spawn objects) on the inside of the wall to give a 20m spawn buffer, keep any 'base structres' ( https://valheim.fandom.com/wiki/Player_base ) out of line of sight from outside the walls and you'll be left alone except during raids and/or you're making loud noises with Fulings nearby. Aside from the occasional Deathsquito since they have massive roaming ranges.
(note with stone all wall parts have equal hp, so a wall made of smaller blocks takes more materials but is far more durable than one made of large blocks).