This seems to be something people don’t always give second thought to. When people talk about the homeless, the first things thought about are images of people on busy city streets in rusty clothes waiting around near allies. In there, the answer is quite static, because it can be I guess. But if that’s the case, change the setting and that changes too. In the places where I’ve lived, people often needed that mapped out. Where are they known in your rural locales?
Mostly in cars. The people that are marginally better-off have old RVs. The people who can’t afford wheels will hide a tent in the bushes. Vehicle or not, everyone seeks out similar places where they are unlikely to be noticed or hassled: lightly-used dirt roads on public land, parking areas at trailheads, closed campgrounds, behind abandoned businesses on the edge of town, etc.