But there won't be any return for 10+ years. 

And get those incredibly good returns?

My biggest fear is that if I ever were to quit my job, I would no longer be able to invest in more real estate (not sure if I would qualify for loans as easily). 

There's some connection you have to this person with money who is looking to invest it short term and collect an x% return. 

At least it will show that someone put forth effort to return the money like you have been trying to do. 

You could easily get 75-80% LTC on the cabin build meaning you'd need about $200,000-$250,000 CASH, to complete the project.Take 200k out of the FL house, build, rent, refi & payoff the FL property again would be my best bet about going about it.

I have a pro forma  using very pessimistic occupancy/booking percentages (worst case scenarios) which identify a very nice cash on cash return, and the ARV will (again, pessimistically) be at least double the purchase+rehab costs. 

Structuring your lease in this way would benefit you by 1) locking in a longer term contract to avoid turnover costs and vacancy loss; 2) it moves your lease end date out of the winter season and into spring/summer of 2026 so it can be more easily marketed and re-rented to match the seasonal demand cycle; and 3) it avoids any upset/angry tenants who may have been incorrectly assuming their rent was going to stay in the $1,200 range after their first 6-month lease term.Would love to hear any updates you have on how this one shakes out for you though!

With broad, high-level criteria, you may be able to easily cross of a number of neighborhoods where the numbers simply do not make sense (assuming you already have your buy box nailed down).

I agree with @John Warren I started in Chicago and expanded to Milwaukee cause the returns were better.