OK people, it's obvious we need a security overhaul. I think I have the simplest idea in mind.
All right, so the mine area has four entrances. If we cover them with four different claims, it should be simple to find a person that holds one of them. Maybe some kind of easy identification would be needed, like a special hat that all claim-holders would wear. Now, when you for some reason need to go into the mine area, you ask a claim-holder to invite you into his party which will enable you to enter.
Before a claim-holder logs off, he finds someone else to take over the claim. When he finds his replacement, he declaims his entrance to the mine area and the new claim-holder then claims it. If no replacement is possible, he leaves his claim in place.
With four different claim-holders that rotate, we have enough redundancy to ensure someone will be able to provide entrance at any time.
The only thing that needs to be done here is to replace the W-E fences made of construction sites with something that can't be destroyed or removed.
Oh yes, we'll also need a list of in-game names of all our villagers, to ensure nobody tricks anyone into providing entrance. I'm Goran Starodub.