At the end of the day, I understand you want to keep a 4.5 or 2.5% mortgage however if you come to find out that by accessing those funds via a second mortage, your overall payments would be higher, it actually might make sense to refinance and use those funds to invest. 

What made this property extremely desireable to me was the 1 mi road frontage on two different roads.

Give the cost of money these days is around 7%, it would definitely be nice to have a paid off rental.7% cost of money sounds like a lot until you remember that it is actually the tenants that are paying it for you while your money is sitting in an index fund making 8%.

I’m a millennial, so figure people can google whatever they desire.

Right now we have enough for a 25% downpayment on 2 $300k properties, and I'm just trying to find the best way to allocate those funds.  

Do you have the time/desire to be a PM for others? 

Investing with personal funds creates a taxable event when you liquidate the asset.

It's great you already have the location, price range, and funding source! 

It’s crucial to stay disciplined here, as overspending on land can limit the funds available for construction and other expenses.Development Scale: I’d recommend avoiding developments in the range of 4-50 units unless you have a very specific reason.

I would also put part of it in a debt fund.