My goal is to continue to grow our rental property portfolio so my wife and I can retire early, travel and spend time with our family.

And did the Turnkey operator encourage you on your first purchase to come out, meet them and walk through the property?

So, with that in mind please consider everyone has a different situation.With a 529 Savings Plan the operative word is "savings".

Then hire a company that does turnkey operations for foreign investors.

Continue to read and listen to the podcasts.

My broker has a few investment properties and I do not act as a "single agent" and only operate in a "transactional agent."

Could also help you over time to start or continue building bank relationship. 

If you don't have a lot to loose, in way of $$$ and assets, than just keep it simple and form a LLC in your state where your doing operations.

@Jason JonesYou may want to consider the be business financing 401k which will allow you to use all of your retirement funds to finance your own real estate operating company without paying taxes and penalties.

It is within 60 days.From my FHA loan:"Borrower shall occupy, establish, and use the Property as Borrower's principal residence within sixty days after the execution of this Security Instrument (or within sixty days of a later sale or transfer of the Property) and shall continue to occupy..."