Thank you be aware that you cannot do a reverse mortgage, there is special training, and licenses required for both you as the lender and the borrower.

Long term rentals don't require full time work. 

If it is a SFR, 60 days notice is all that is required.  

If there is landscaping that requires upkeep, there is a chance the tenant will not want to do that and over time it can become an eyesore. 

certain wholesalers pray on newbies, and rush the entire process so you do not have time to do the required due diligence. 

Investing requires a bit more skill with how the market is these days.

I will note that some of the information on here will be different for you especially when it comes to loan products and requirements so that is something to keep in mind. 

Any conventional loan products for property in a flood zone (not sure what flood zone 9 is) requires flood insurance, which can be very expensive, and rates have been rising each year. 

First someone new will be living with you and that requires adjustments.Second it's not just someone, but rather it's your in-laws which can bring stress to any marriage good and bad.Third your introducing a money factor into a highly personal relationships. 

If not FHA, you could use it for your next purchase and the owner occupancy requirement is 1 year, not 2 as you mentioned.