I will say, services are much easier to obtain in the metro vs vacation market. 

I have just over $200K left of owner-financing, but I'd like to obtain a cash-out mortgage/loan of $500K (ideally) to be able to pay off the previous owner and make some repairs, etc. 

It sounds like you will have an issue obtaining financing.

This will effect your ability to obtain financing for quite a few years but may be worth considering.  

Yes, it is possible to obtain a second FHA loan, but only under specific circumstances, as FHA loans are designed primarily for owner-occupied properties.

Depending on your level or preference of analysis, data and their providers are incredibly important and difficult to obtain when it comes to real estate underwriting.

Fix-and-flip or builder’s risk insurance should be in place before work begins, and confirm your contractor obtains all necessary permits to avoid delays.

If you are looking to just obtain the 25% redemption rate set by the state for properties that are limited to 6 month redemptions.

if anyone has successfully obtained a second mortgage.

The way the guidelines are written is that you have to intend to occupy the property as your primary residence when obtaining the loan, and this is generally demonstrated when you live in the property for at least one year.