"Occupancy and Use" - A Deadly Leftist Fallacy

In one of my last blog posts I mentioned something called 'Occupancy and Use' theory of property. This is a kind of strange concept where in order to own something (as personal property) you have to first acquire its use through something similar to Lockean homesteading and then keep using it. If you stop using the property it is considered abandoned and anyone can now get their hands on it ('re-homestead' it, so to speak). Occupancy and Use (OaU) is favoured mostly by leftist groups such as left-libertarians and anarchists. Famously it was the position held by Benjamin Tucker and other individualist anarchists. Now I see more and more people (who usually describe themselves as 'Mutualists') subscribe to this theory. In fact, a couple of my friends have recently argued with me about this because they seem to have become converts to this new faith.
But the OaU makes no sense to me at all. Not only does it seem illogical and weird (from my Rothbardian perspective), but it also seems impossible to put into practice. I think the whole point of inventing OaU was to eliminate rent in land. Rent, usury, and profit are, of course, perfectly legitimate; but socialists have been trying to purge the economic sphere of these essential elements. So what are some questions I have about OaU?
How is it possible to determine when someone is allowed to re-homestead a thing? If I take my dog out for a walk and come back to my house just to find a group of gypsies sitting there, can I kick them out? The squatters would argue that I left my land unattended and therefore I abandoned it. I really don't understand how someone could make such an arbitrary decision as seizing someone else's property! And what then about other items? I only use my vacuum cleaner once a week - does that mean that I don't own it on the other 6 days? And what about the food in my refrigerator, I'm not currently eating it, so can someone just homestead that? This just seems silly to me.
And how can capital accumulation take place in such a society? We all know that without capital accumulation investment is impossible, and without investment there is no economic growth of any kind. Clearly the very definition of accumulated capital is capital which is available for investment because it is not currently being used by the owner to satisfy his/her present needs.
But under a system of OaU if I tried to save up a quantity of anything (particularly land) I would be committing a immoral act. People would have the right to take my surplus goods or settle on my surplus land. Is this 'hand-to-mouth' reality really one we want to live in?

Am I missing something here, or are socialists really that crazy?