I guess a flat seasonal fee like any insurance policy, sometimes you win, sometimes you lose.

Before you close, can the rent from your buddy and the midterm tenant cover your mortgage, taxes, insurance, plus a bit extra?

If you research recent sales you can always provide the appraiser a list of those sales.One of the best ways to insure a higher value is to update the property using materials and fixtures that are popular and common in the area.

Your insurer could recommend one or you can check Google (and, of course, the reviews).

@David R Pustelnik recommend you first focus on raising the rent for the first time in 10 years.By the way, how much have your property taxes and home insurance gone up since this tenant moved in?

Laws, taxes, insurance, adventure, new challenge, grow skills, etc. 

Insurance Agent8.

Tax accountant, banker, realtors, property manager, insurance agent, etc.  

Got insurance involved and use that money to remodel the entire inside, and add a new roof.

To make a new property cash flow with current prices, interest rates, taxes, and insurance, you're putting at least 40-50% down.