- Will they be my KP on the loan for a small piece of the GP?

In those cases, if the market goes down, you are willing to hold long enough for the market to rebound.My second piece of advice is to only buy properties that you would live in yourself.  

To lead this process of decision-making, formulate distinct preconditions for investing, among them cash flows, expected returns, tolerance of risks and investment timelines.Good luck!

As @Jay Hinrichs mentions whether a piece of land is land locked (no street access without crossing other land) would be a  matter of a survey or check of tax plats.

Since you're selling 8 SFRs, this could break up into multiple distinct exchanges (most likely), but you have the option of combining multiple sales into single exchange purchases. 

As my wife and I are both over 45, we require a distinct approach to ensure we can retire within the next 10-15 years without having to work, particularly in physically demanding jobs, until our final days.

As long as the distinction stays clear in your mind, I think you will avoid any serious pitfalls.

I feel like that piece would be pretty tedious.

Now you guys are the only missing piece, what would you sell it for?"

important that there is often a distinction (however vague) between first time "investor" and first time "homebuyer" - always have to confirm if/what the difference in program eligibility is