Your dwelling is a soft, tempting, easily detected target. You have to watch 4 directions, 24-7, and that means that you need at least 8 adults, doing nothing but watch out the windows, in shifts. If you build a protected tower on the roof, you will be exposed while you do so, make a lot of noise, have a lot of movement to attract attention, and the wt of all the sandbags might well cavein your roof. Once you get such a tower, however, you might be able to get by on 2 adults, who do nothing but stand guard and rest from having just stood guard. Each adult will of course need some sort of effective night vision, with its burning of batteries, especially cold weather. All a guy has to do is get within 300 yds of you, at night, even with a clunker milsurp bolt action, wait until late afternoon the next day, snipe you, leave after dark. He can make a ghillie on the spot, out of his poncho, hammock and local vegetation. It takes only a couple of hours. He can dig a shallow trench to lie in, and you won't spot him, even with binoculars and if you know where to look, at 300 yds. If he knows enough to use cover, all you'll have is a head shot at that range, and if you miss, all you'll have is a dodging torso as a target, and you won't hit that, either. He can return at leisure, bringing friends, etc. You will still be there (unless somebody else has shot you or burned you out in the meantime).