This choice changes the situation for the lender into an equity partnership which increases their risk, which deserves a higher reward, in equity, cashflow and sale.In any case the lender should be on title (like a bank would) to secure some or any colateral.I am a multifamily real estate business owner and not a legal expert, therefore any agreement should be drawn up and executed by an attorney specialized in your field.

In fact, this does increase their tax bill because of the interest on the loan. 

@Matt Smith Hey Matt, A few items here: You can always offer the 80% of the listed priceThere is already meat on the beat, it is the $500 less than what you're paying right now, and YOU (no, sorry TENANT) is paying down your mortgageDuplexes are hard to come buy in your area [you found one of the unicorns-this is a sign lol] One item to watch is the number of rooms and bathrooms, which could increase your ongoing maintenance expenses, but you already have some capital set aside so you've got that covered too-you're rock n rollin!

I am looking to invest in the area more but right now it's difficult because the prices are so high and renters are maxed out on what they can pay. 

Seems scary to take on any additional debt unless unless if you have quite an increase in cash flow or an amazing opportunity due to currently being in a debt repayment plan.

It’s going to be difficult to really push the ARV higher than what you paid unless you’re willing to wait 6-12 months

Interest rates shouldn’t increase dramatically over a few months, but this is your call.  

It will be your cash flow and with the cash flow you can refi to increase your number of properties. 

How difficult is it to find deals in Jax and around?

To answer your question its not only difficult to fund the right project but more important is finding a good borrower.