In my opinion, it is better to choose an area with a path to progress. 

Would you be better off just writing VRBO a check?

I wouldn't take that money to buy him out I'd liquidate and move into better asset class like extended stay development or 3 story walk up apartments 

Are there any resources available and recommended that would be better suited for creating a pro forma for new (spec) construction?

These don’t GUARANTEE success, but provide a much better chance.  

In my experience, the local banks are going to get you better rates and lower fees with their commercial loan products than the "DSCR lenders".

A great lender can help you strategize and get much better ROI. 

Same thing with any investor you get in bed with.With time you can work some equity into those rentals and when interest rates come down you will be in a better spot to sell a couple SFHs.   

A turnover means repairs, painting, cleaning, marketing, vacancy time, and lost rent, so a small discount is often a better financial decision than churning tenants every year.There’s a lot more to consider, but these are some key lessons I’ve learned.

Also, don't complain about your offer not being accepted - just submit a better one or walk away - the seller doesn't care about anything other than how long its been on the market and how close to ask you are.