However, it’s important to ensure the area is safe.

The best way to connect and learn is to be in rooms where it's going down.In terms of captial your best bet is to focus on a primary income that cash flow sufficiently, saving as much as you can and doing something real estate related so you can get familiar with the industry.

Quote from @Brandon Foster: Hello Ryan,STR is do able in the north county area but there are a lot of rules and regulations.The city of Oceanside right now will not allow anything STR unless it’s west of pacific coast hwy.This is changing a lot too so you need to be aware of that in your plans.Carlsbad is super strict too but there are some condos that are still available to do STR in.Medium term rentals are as safer bet but way less profitable.

That’s the best bet.

You're best bet is to call a few brokers local to the area and see what they can come up with.It's definitely going to be a surplus or excess carrier that will do it and the premiums will be high. 

I know that the general guidance is that emergency funds aren't to be invested, but given our financial security and the fact that we already have a personal e-fund in a safe, non-volatile location, would it still be crazy/unwise to invest this 15k in an S&P500 index fund in a brokerage? 

Make sure the location is safe first.  1.  

That’s the best bet.

its highly risky for most mom and pops to sell on sub to.. and its simply not a way for those without substantial wherewithal to buy property and keep the seller safe..

I'm betting he'd drive to that area.