I don't know of an outline that exists like you're describing.

I would attempt to save the existing drain field, perhaps it may only need to be flushed; have your septic guy give you some alternative suggestions and make the replacement the last choice as it is the most expensive.  

In my case, I opted to pursue markets where I had some knowledge and some existing connections vs. trying to find the best market and build a network from scratch.  

Something seems off but we do not know the terms of this 72k note…….. your potential proposed structure of paying the 53k down , what would that do for him anyway since unless the loan is going to be recalculated to lower the payment, the payment exists ( and I’m assuming its small) which does not explain what the stress is from it.You say the owner is motivated.

You could transfer your existing IRA to a self directed IRA or Solo 401k and invest in real estate (or anything else the IRS rules allow for).  

All the cash flow from my existing properties stays in the bank account for each LLC.

I have to imagine a few active groups exist there.

This favors the conventional loan because when you refi down the road, you'll be stuck in the interest rate environment that exists down the road, whereas you'll keep today's rate with the conventional.  

They exist and probably do in a surprisingly large number when you look at the whole state. 

Sometimes the existing tenant is neat enough to do showings while they're still there.