The house will surely continue to appreciate while I either rent out the property or Airbnb it. 

Are there lenders that will do a cash out on a property with no mortgage?

But since I front 600 feet of his property it was important to him to have input on design and quality.

In the long run, that property will go up in value and this may be a viable option.

Any referrals for agents, property management, and other area professionals would be much appreciated.

This BP topic, Total Available Market - 2, 3, and 4 units, describes the Raleigh market for property that meets Fannie Mae 1-4 Family underwriting. 

Ask anyone with investment property and they'll tell you it's not passive.I earn enough from investments that I could be financially free for life, assuming nothing major happens.

I would offer 90% of the market value. if he sells it you with no agents he is saving 6%~ on real estate agent commission and the other 4% is a convenience fee in that he dos not have to endure showings etc. and you will get better pricing on a non-owner occupied property if you put down 25% is compared to 20%.  

My parents have been very involved in the purchasing process- touring the property with me, etc.

Also, the lender won’t take back the property in leu of payment-we asked.