Territorial behavior

We got our 7 month old rescue 2 months ago and have worked a lot on different socialization – walks, trips to parks, pet stores, etc but something that is still really hard is he's very territorial. He is a mix of 50% mountain cur, 30% American pit, and then small amounts of plothound, Staffordshire terrier, coonhound. When people pass by our house he barks a lot, he barks whenever the neighbor walks his dog outside, and when people come to visit he barks almost the whole time. He will bark, and then come sniff, relax or focus on other things, and then go back to bark at them, or anytime they move to walk around he will bark. He has also started to bark when we pass people on our walks and I don't want this to escalate, and also I'd like to in the future have a dog walker but I don't even know how we'd do that at this point, I think he would bark at the person, then settle but then the next time they came he would just bark again. And as I said I don't want this to escalate, in the past he has been so nonreactive while we're out I don't want that to change