Covenants can only exist if there's a party to enforce them. And that party has to be paid, since preventing people from doing something costs money. Unfortunately, often the government takes that job upon itself (as in Houston).

A more realistic and free market-oriented approach would be to force people who want access to their neighbor's property to...buy it! Sure, it would encourage people to own larger plots of land, but given the inherent perils of homeownership, I'm not entirely sure that converting a nation of homeowners to a nation of renters would be such a bad idea.