Actual safe base

Zombies want to reach the player. They only attack blocks insofar as they’re seen as an obstacle to getting to you. Design your base such that the zombies have a path where they would eventually reach you, and your base will only take incidental damage. You can also adjust the zombie block damage, including just during Blood Moons if you want, as I recall.

If that’s still not good enough, then cheat and build your base out of bedrock I guess. Or mod the game. Either way you’re rejecting the idea of a 100% destructible world, but to each their own.