There is easy solution to all this problems with base raiding:
Every base should have "claimfire" build, without it its not a base.
Claimstones need to be connected to each other (zones overlapping).
In this overlapping zones there should be "claimfire" object. There should be a limit on how much fuel this claimfire can store (lets say 24 hours). If fire is burning, connected claimstones have 999 strength, if not, server defined strength.
Once first block looses its first level hp (you can upgrade wood frame twice, each giving you 200hp i think, that makes this object loose its first level hp after destroying its first 200hp), claimstones make all blocks invul and you cannot refuel (or turn off) your claimfire until all the fuel is gone and all the blocks are repaired (you can only repair your blocks if claimfire is turned off).
So every time you login, you put on your claimfire amount of fuel you want your base to be protected with. In this time, attacker can start raiding, but has to wait for said time for base to be raidable. With some timer notice, attacker knows when to be online to finish things, but also you can be there to defend it.
As far as PvP goes, current implementation is OK, apart from hackers. Last time I got killed, I managed to kill that person back and his gun had 450 bullets in magazine for example.
