I recommend providing a preferred return to the funding partner.

Dont mix personal and business funds. 

We also will have around 7 more SFR's within the next 8-10 years that will not require any out of pocket funds from us aside from legal fees to transfer ownership.I would like to begin focusing on flipping after summer of 2018 to build some larger cash reserves for purchasing more LTR's.

As for investing it into a ETF or mutual fund, it may go up, or it may go down so if you're planning on this loan being the key to start your real estate investing have a backup plan in case the worst happens.

They might be interested in obtaining these funds and if they are in this legal limbo area, you have some negotiating power.  

Due to our limited funds, we want to figure out how to get a great deal, with as little of our cash in the game as possible, to allow a "safety net" of sorts.

Moving forward, you should try to have proof of funds already lined up.  

I am also open to Partnerships or funds so if there are groups or firms you would recommend with good reputations of success who work with informed investors that would be helpful as well. 

@Joshua Rountree - Not sure what you're asking exactly, but I'll try to help based off what I take away from this.First - the offer would likely have to be under your partner's name since a cash offer will require a POF which the names have to match the POF and the offer - otherwise you could just be taking someone else's bank statement and saying they will fund it with no legally binding contract.

I also need to settle on what type of funding I want to do and get that lined up.