My personal capital is tied up in another BRRRR at the moment, so I will need to find a private or hard lender to complete it...

The past is over, you stepped in it, and you can't scrape it off your shoe. 

Search BP for skip trace tactics and tools.Mailing letters/postcards to agents (bring me your too low equity to list sellers), long days, expireds is expensive and takes a long tie to get that seller to call. 

If im using 2.25% down payment, it leaves me with high cash on cash return and higher mortgage. cash flow after 50% rule is $115/mo. this doesnt leave me with much room. if you were in my shoes, what return would be acceptable for you?

Do I have an agent draw up a rental and a buy contract, can they be tied together?

First, it’s delusional to think you’ll buy a $100k plus house for $3k at auction...there is competition and the bank will have a minimum acceptable bid, likely the mtg amount.Also, you really shouldn’t be tying some person’s property when they are facing foreclosure if you can’t and don’t actually plan on buying it.  

Real private money lenders know how to do basic math and determine when and how their money is going to be tied up. 

@Anthony Lambert If I were in your shoes, I would see what types of meetup groups are available near you!

I know that they have a good amount of equity tied to their property after they shared their purchasing price with me.

He's right, the RTA doesn't apply unless there's a residential lease tied to it.