- Because you have to fear someone will rob all your resources, destroy your base and bomb you back to Tier one while you are off-line one can not build large visible bases or farms so I would guess that the best concept is to run as far as possible from server spawn, find a natural cave so no one can follow your track and more or less hide.
- Because leaving mine shafts open would direct anyone directly to your base you would have to replace any block of stone you dig or mine far away from your hidy-hole.
- Building farms or huge machines is only "save" if one spreads them so loosing a kiln does not mean your pottery and soul-bottler are gone too.
- Defending such an array of not connected mini bases is of course impossible, you can not be at two locations at once.
- Building traps is only effective for one hit because after the location is known the attacker can simply dig around it or wait until you go off-line. So camouflage is the best bet.
So one can not effectively defend his base or belongings and the only way left is to run for tech supremacy and keep anybody else from reaching the tech level necessary to harm you. But because explosives are cheap and easy to get its just impossible to keep an opponent from gathering a stack of sand and hunt down a few creeper.
And if one gathers a bunch of his friends they could easily camp the server spawn point too. So I really do not see the fun in playing a build-machinery and tech-tree based game-mod in an environment which enables the willing to destroy everyone's achievements with low tech (vanilla) stuff within a minute after he finds a base or building.
So based on those assumptions I do imagine an Anarchy-Server to be like a strategy game in which everybody has End-Game-Weapons in their pockets waiting looking for a Steve to send back to spawn.
So please enlighten me.