What difficulty and gamestage are you all on? Tbh, I've seen progressively more and more wandering zombies the higher my gamestage goes - up to the point where I drive around and can't go a couple seconds without running into a few or a wandering pack. I still think it should be a bit more, perhaps earlier than what it has been anyway. Honestly, on the harder difficulties and horde night spawn counts I don't think you'd fare too well without a base, unless you spend a lot of time repairing POIs.
I really feel you about sleepers. Tbh I don't like them at all, aside from maybe a few of them here and there for scares - that's always refreshing to have a jump scare time to time. But there really are just too many sleepers, although they reduced them, I think just having a lot inside there along sleepers here and there in surprise parts would make it more fun. All sleepers... meh. I'd prefer a "trigger spawn" of a random horde kinda like the supplies quests do to send some zombies into/around the POI you're in.