Invest your money in a better deal. 

It cost us more money than we would have liked to have spent, but we were able to put a house on the market that we were proud of.

I see hard money lending as just part of the cost when doing these kinds of deals.

Consider financing options like hard money loans, or FHA loans for house hacking, and focus on areas with strong rental demand near the MA/NH border.

These are some of the most successful people; CEO’s, tycoons, celebs, old and new money and investors on the planet.

Selling it now vs renting, will give your dad more money and he won't have to worry about renters or cap gains. 

I would be less concerned about the cheapest money and more concerned about decent terms and execution.

In fact, I would estimate that it is mostly upper middle-class folks that have the money and wherewithal to go through the vacation rental process - prepayment of substantial monies, etc.If you only have one property, I would just stick with Venmo, CashApp, or Paypal.

Do not waste your money on his course.  

In most cases you will loss money (in the current year) if you need to turn a unit for a 10% rent increase.