I recently got into my first deal with a private lender in where he was willing to co-sign a conventional loan with me and fund the rehab of my first house hack for a percentage back. 

I was initially wanting to receive a conventional loan and pay a downpayment in cash from savings and buy and hold properties. 

It's also very close to Reed College, a $60K/semester school, so it would be a strong draw for wealthy visitors, campus tours/visiting parents, etc.Also- my primary job is an online merchant, selling on Amazon/Ebay and I require a large space for daily inventory/shipping prep.

However after crunching some quick numbers, I’m trying to understand the benefit of a cash out refi vs just getting a conventional mortgage.

This is an old link I found but serves well for our example) Let's assume that at any point, 10 percent of this inventory is for sale (no data found on this but any number should work).

Conventional home loans are the closest thing to free money as there is. 

Others will let you put conventional mortgages on 10 properties.There are also banks that lend on 20-30 year terms as portfolio loans which means they don’t sell them to Fannie or Freddy and therefore there is no limit to how many you can get.Another Avenue is commercial lending.

Some marketing takes a bit of time and money - I'd like to be sure I'm taking the right approach when it comes to a small town with limited inventory. 

We just purchased a 3rd SFH using conventional Fannie Mae financing with 5% down.

Holy moley we’ve got some inventory!