There is no reason to make a visible base, because once a base is found, it is dead.
1. For underground bases people should be given an ability to limit the vertical dimension of the claim volume. So players could not hear the "claim sound" and see buffed voxels by hitting ground and trees above.
2. To make it difficult to find where the claim block is people should be able to decreas the claim dimensions and make, say, 5x6 inctead of 7x7.
3. Attacker respawns should be balanced. It is now easy to just drop a bag and deplete enemy defences ammo / power. People should be allowed one infinite fast respawn at their main base, and their spawning on "raid bedrolls" should become much slower if they get killed near someone's base. Like, + 30 seconds, +1 minute, + 3 minutes, +5 minutes.
4. It is possible to just lure a horde of zombies and let them make a hole into an enemy base. This should not work against offline protection.
