But if you acquire property legitimately, then there's no problem with it, even if it's not constantly in your possession, or occupied by you personally. Anything else would just not make sense. For example, if you park your car somewhere and go shopping, will the car cease to be your property just because you're not in it?
On a fundamental level, property can be thought of as "value you want to control". Something has value, and you get to benefit from it, because you've either produced the value yourself, or you've acquired it through a voluntary exchange (or contract etc). You build a house, the house has value as a dwelling, and you want to benefit from the house by either living in it or selling it to someone else.
That said, I'd love your opinion on taxes, volunteerism, and force. I think many anarchists are utopian statists who don't realise how important it is for an anarchist society to oppose the creation of central authorities and the formation of "too big to fail institutions". Love your thoughts on that.
1) Any land covered by something valuable that you "produced" yourself is your property. A house, a corn field, a copper mine, etc. But land in a state of nature is not. For example, 10 acres of forest in a state of nature would not be your property, because you haven't "mixed your labour" with it.
2) Even that 10 acres of forest can be your property, and you get to control (access to) it, because you need to know that you will get to benefit from any value you produce with that forest, even if it takes some time to get started, let alone "materialize" that value. Maybe you're planning to build an amusement park, but need to figure stuff out first, and make sure you'll have everything you need before starting the project. Maybe that will turn sour, and then you'll switch to some other goal with the forest. But if you don't have the right to control (access to) the forest before you do something with it, then you just won't do anything with it because you have no guarantee of getting to benefit from the value you produce. The latter case would be a loss to other people too, because something they'd benefit from (even if in exchange for a fee) would not come to be.
I think both 1 and 2 make sense.