Minecraft wiki entry for Multiplayer_PvP_bases, associated text: The above method of making a base can actually be applied to all bases, and thus, made even safer. You can transport elder guardians using minecarts or boats to your bases in other locations, to prevent break-ins.
The disadvantage to this method is that the mining fatigue can affect you too, so breaking blocks will be extremely slow for you as well. Drinking milk can prevent the effects for a short time, but that also means that raiders can do the same.