Welcome to the forums, this is so great I see questions about design all the time and I've personally experienced the design paralysis myself.

I’m Zachary Petty, a DSCR loan broker excited to join the BiggerPockets community.

All of the above? 

In the end you always end up paying somewhere between 8-12% on your money. 

I put roughly 20% down on a $200k home, and am curious what steps I could take to possibly turn my original investment into a large portfolio within the next 10 years, when we're currently "low on liquid funds" after finishing up a wedding.... 

I wouldn't touch anything outside the urban core. if your strategy is to buy existing and old I'd recommend not to. as a newer investor depending on your liquidity look at build to rent development. building investment properties below market value by 25% and refinancing out of it to do it again. the urban core has tax abatements as well that are 15 years right now you can apply for. that means that taxes will be around $600 to $800 per year. there's cash Flow but the existing inventory market dried up a few years ago in the urban core. local realtors are going to push you to the trash areas like hilltop, south linden, etc because it's the only place numbers work. columbus is great, but remember a tenant who pays $1800 a month is different than a tenant who pays $900 a month. let me know if I can help any other way! 

This allows me to pay off the private loan (~$550K principal + $49,500 interest).

Be prepared to come in with additional cash to close due the the appraisal.   

You’re all set just the way it is.

@Jeremy Bohnett most lenders will refi up to 75-80% LTV after you have rehabbed the property and have a tenant in place.