But I'm 15 years in and debt is decreasing rapidly.  

I expect to see an decrease in market, then an increase after the residents have regain normal lives, maybe 5 years timeframe.I'm judging from my local market after a the 2011 tornado.

Tenants then leave or renegotiate rent downwards causing a new cap rate of 8 and now the value of the property has decreased. 

High initial cash flow that decreases over time.IV - High Demand, Limited Supply: Prices and rents will tend to exceed inflation.

The New York Times just posted an interesting article with the extremes in increases/decreases of residential building permits across the US.

The population of New Orleans fell from 484,674 before Katrina (April 2000) to an estimated 230,172 after Katrina (July 2006) — a decrease of 254,502 people and a loss of over half of the city’s population.(1) By July of 2015, the population was back up to 386,617 — 80% of what it was in 2000.Several-hundred-thousand people moved to Houston in the last several years.

But, nevertheless, the decreased monthly expenses was equivalent to giving myself a tens of thousands of dollars raise each year through this version of a house hack.

Zain, decrease the risk you are taking and put the liability back on the contractor.

If you train your tenants and set up systems, you will be able to decrease your time commitment.

Therefor selling some of your non performing assets, or places that are geographically far from your residence (you mentioned they are scattered all over the valley) and paying off the loans on a few of your existing properties, thereby decreasing your leverage could help you in two ways.