Most capital partners are going to want mortgage loan involvement to reduce cash outlay for a deal, and mortgage lenders are going to scrutinize your cash position going in, so the first step is to get your cash ducks in a row with the capital partner/investor.

When you sell, you are doubling the number of properties each time, doubling the PV and the CF.Doing REFI's is a linear return, with a step back (reduced CF on refi property)Doing flips is a compounded return.

Keep in mind with rates dropping on cash out refinances since they reduced the LLPA hit a cash out refinance may be a better choice over a HELOC.  

I'd also add a vapor barrier to reduce humidity in the crawlspace. 

Your job as the leader of that business is to reduce that risk as best you can.

Speaking purely from the standpoint of you qualifying for another mortgage, you at least need to charge enough to reduce your debt burden and get your DTI ratio below say 50%. 

Understanding who your target audience is or will be will save a lot of time and energy on where to focus your efforts.

Prior to Real Estate, I was in the midstream energy asset development business.

If you want to check this logic you can reduce your mortgage interest rate to 0% and see the difference in your numbers.

Whatever you do, just be aware that "not raising rent" means you are reducing your net income every year.