The high PM costs can absolutely be justified. 

One of the most surprising experiences I had was when a borrower with a seemingly high-risk property came in with a last-minute change to their scope of work.

However if are dead set on Owner Financing, you have to get get 20% plus down payment and if you are in Florida, you have to deal with a Judicial foreclosure process which is not nice to Lenders, I would highly recommend against it.

Your offer should match the type of person they are.

Offering a cash-for-keys arrangement (what would be a reasonable amount?

I paid off almost 6,000 in a high interest credit card , The next day my credit score dropped 90 points. 

I'm not sure hot tub would be a good bracket to place a soaking tub, as pointed out hot tubs offer more than what you have pictured.

Financial goals: Our current jobs provide for high-income but not a lot of time for active real-estate investing, so our strategy is long-term buy-and-hold with less headache properties.

Highly recommend @Eric Prine!

Owners mistakenly ASSUME all PMCs offer the exact SAME SERVICES and PERFORM those services EXACTLY THE SAME WAY, so price is the only differentiator – so, they often select the first PMC they call or that calls them back!