Or did your SO make a $50-100k mistake by not seeing that it did?

So they used the actual rented data of these companies to compare what rentals should go for in your market.

And it was purchased with primary residence financing - so advantageous.  

This will give you some info so they are not guessing on what will be needed (they probably already know rough numbers, but each project is different).

However, as noted, there must be 500-1500 investors out there, so why are so few represented on BP, so.....Curiouser and curiouser.........

Refi the house so they can continue to live in it, they will get the best loans on their primary residence.

Once your portfolio gets so big, you will need organization of your financials not only for tax time but also for your day to day, month to month decisions.

Out of state investors can do really well here, but you can also lose a decent chunk of money if you buy wrong.Lots of out of state investors, especially those from California get a little blindsided because everything here is so cheap it all looks like a guaranteed great deal.

I say this not to discourage you, but rather to encourage you to prepare for what lies ahead so that you have the best chance of success. 

There is so much to see and do there.Murrells Inlet has many great seafood restaurants!