Try to narrow down your options to the top 3-4.

Real estate investors have a variety of financing options available to them, depending on their financial situation, investment strategy, and the type of property they're interested in.

If not, do I have any other options at 20% down? 

Options? 

The 10 doors are also not appreciating because they were turnkey and the 1 door is in a vacation area and appreciating.You should be hunting assets because strong assets give you multiple options.

Now, if this coach is going to co-GP your deal, bringing their balance sheet to secure a loan, investor connections to help raise the money, asset management skills, broker connections, etc to actually get a deal done, then maybe that is worth the share of profit, but most guru's I hear about are available for questions you bring to them, and put you through a generic course, typically with market selection information, basic underwriting education, etc.  

Your budget of $600k would afford you a number of other options in the Myrtle Beach and North Myrtle Beach markets. 

I think refinancing would be a better option.

lets look at renting and refinancing options 

Ok refinance is the better option.