Alternatively, I could liquidate stocks to pay off the property but I'd be subject to capital gain taxes and obviously not leveraging.

Of course, you could also make the seemingly-reasonable counter-argument that you would have to have proof that you sent the letter, and how could you get that proof if the letter were to be forwarded (to an address not provided to you by the tenant) instead of being returned to you for you to use as evidence later that the last known address was a dead-end?

Like dead heirs they can get releases from, or mistakes in the contract made by an agent/buyer/seller. 

For stock investments for instance, just invest directly.

Mortgage rates are driven by The 10 Year Treasury so in order for mortgage rates to go down, we need to see “investors” pull money out of the stock market and put in to the 10 Year.

I have looked into AirDNA and AirBnB estimates and I want to know how much stock I can take with their estimates?

Behind the scenes, the industry calls these provisions "the seven deadly sins." 

I think it's smart to put money into the stock market.

Else, it doesn't help me a lot since my other investments in stocks, etc are doing pretty well. 

We usually stick to either refinishing the oak floors, which are very common in our 1960s Milwaukee housing stock, or quality LVP and LVT - especially for kitchens and bathrooms.