You have proof that you sent a letter to their last known address, a returned piece of mail. 

This is an important distinction because it allows you to maximize your tax benefits across your portfolio. 

When I see a property starting to underperform, as the manager I have to run the data to figure out why and then make adjustments whether is lack of amenities, need updated photos, replace a couple pieces of dated furniture or increase my focus on advertising that property specifically.

You will need to do that anyway to get them to plug in the equity piece.

One of the terrible pieces of advice I received was from 2 people who suggested that I sell my California SFH rental (with lots of equity) to "cash flow" more and "acquire more doors" by doing a 1031 exchange into an apartment complex OOS or buy multiple SFHs/duplexes OOS.

Paid $800 for a structural engineer to write up a 10 page piece of fluff telling us all the ways we could spend money to fix the sinking but settled foundation.

One is a house, the other is a piece of land that has a condemned trailer on it.

YES, that was the whole thing, shovels and wheel barrows, literally, not 1 piece of machinery was used. 

I'm getting decision making info in only small pieces over time, via phone calls only.

Each piece locks together to its neighbors.