What I'd do is Airbnb it the popular months from late spring to early fall and then plan to get a medium-term renter in there for the remaining four months. 

Lower down payment requirements but you have to live in the property for a year, no big deal if you plan on house hacking for FHA.

It has extra land where we plan add another 1-3 rental units.

The quickest way to see what you can do is to go talk to an architect/engineer and run your plan by them.

We plan to fix up each unit as they open up and raise rents to market.

It's possible for certain sellers to fund the sale of a home, so you can buy real estate without depending entirely on conventional financing.It's critical to get advice from real estate agents, financial advisors, and other specialists before making any decisions in order to customize a plan that fits your risk tolerance and financial objectives.

My plan is to immediately move the three lower units to $1400, then in 6mos move to $1450, then a year from now, bump them to $1500 (leaving the one at $1550).

It turns out I don’t plan to ever touch the money, I should have invested it in more real estate, but I was a young and dumb sheep. 

That sounds like a plan! 

Knowing what you're looking for and having a clear plan in place for what you want will surely help.