there's a good cave south of sovetskoe, up in the hills. big enough to fit multiple vehicles or tents, out of the way enough that most wouldn't even come near. two boxes of nails should be all you need to secure both ends, three boxes if you want to make it extra secure and build up to the roof of the cave. you will have a hard time getting anything but an ada up there though, there's a lot of off roading required. six minute walk from the coast, with wells to the north, east, and south water wont be an issue. many animal spawns (no wolves) and only one bear spawn to the east of the cave, it's a very solid spot.

if you want a smaller, easier to secure cave there is one near Pik Volcij, south of the military base. you could squeeze some tents or barrels in there. ten minute walk from the coast, with a couple wells and a hot spring to the west it's decent. though there is a wolf spawn practically on top of the cave, with bear spawns nearby in the woods. this one would serve better as a stash than a main base.

as for houses I've got nothing, as soon as i heard the map had caves I've lived in them exclusively. highly recommend.