I think frame of reference here is important when we talk about private property rights. You obviously want to frame this as a discussion based on a dense, urbanized population. To do so otherwise would be to fail to "distinguish between abstraction and reality"

But we have lots of examples of private property with a lack of government support. The early history of the United States was almost completely without lots of local civic support of private property rights, yet private property rights worked just fine. In absence of the government, I have the duty and obligation to protect both my private property rights and those of others. I could go on, but we can all agree that private property exists quite well without government support. Take a look at criminal activity and ownership, or ownership of explored lands during the Age of Exploration. (Now you can argue that the natives weren't given much private property rights, but that begins to diffuse the entire discussion. Let's stipulate that once people owned or took possession of things, they mostly held on to them just fine)

In the same way that strong private property protections are a bedrock of western civilization, you can throw in "decent behavior in public"

Not really. "Decent behavior in public" is only relevant in regards to how it relates to private property. We always get back to private property. And yes, we threw chamberpots out the windows for a long time and civilization went along just fine.

People are free to think of me as an inconsiderate ass. I welcome their disdain. That's the entire idea -- others' opinion of my behavior should be non-relevant to my life as much as humanly possible.

I think you're confusing a couple of things here. I am not trying to "win the pro-property-rights argument" I'm not a politician. I'm not a good orator. I'm not especially good at persuasion. I'm simply pointing out that private property rights are the bedrock of modern societies. This exists with or without my consent, support, influence, or whatever else.

You seem to be rambling around a bit, or perhaps I've done a poor job at reading your post.

There is an interesting inverse relationship between population density and available freedom of ownership. I can't own a loud dog if 200 people live within 50 feet of me, yet owning one on a farm is non-controversial.This doesn't mean that the basic amount of freedom required by the individual for a healthy and dynamic society changes, it just means that compromises have to be made. That's my point: saying it's relative and political and all of that is somewhat true in application, but the underlying principle has hard limits somewhere and with a constant drift towards less freedom we are bound to overrun it -- if we haven't already.