But they accumulate when I am on vacation a few thousand miles away and cannot just run over and check it out.

It's absolutely unbelievable the capabilities AI have accumulated in the past few years!

Commercial loans offer a higher LTV (85-90) than conventional loans (65-80) and are easier to close on, so they could have helped me accumulate more properties with my limited cash on hand.

You need to get over your fear of rehab and force some appreciation, both on rental properties you purchase, and also possibly on flip properties to accelerate the accumulation of capital to invest in rentals.

Live where you are and start accumulating rental properties.

His opinion was that using a hard money or private lender so there's a loan to finance was the best way to go if I want to accumulate properties quickly on the best terms as long as I don't mind having them in my name. 

You are on the right track yo just need to build up a rental history so that you will be able to refinance your properties   The equity will accumulate over time. 

I've spent the past 4 years overseas in a deployed environment as a defense contractor, trying to accumulate enough money to fund investments that will generate enough passive income for me to achieve my goal of financial independence by age 30.  

The only thing you have left is the experience, insight, and wisdom that you've accumulated over the years. 

So far it has been 2 years that we live in it and couldn't be happier about what that lifestyle is giving to us in terms of freedom.Our experience with real estate for the moment is that we built that tiny house by ourselves and by doing so accumulated quite a few construction skills.