Someone will need to cut the grass, fill pot holes, make sure the roads are not collecting water or eroding, test the water supply monthly and send the samples into to the state.

I've used a number of GCs for full scale renovations over the past three years and while there are many I can whole-heartedly renounce, two have stood the test:- Paul Little Construction --> solid processes, good use of subs and oversight of subs, usually within 5% on time and 10% on budget. 

Here's the Qs I ask all those I consult when asked this question:FSBO Self-test Check – Is it right for you?

No broker will even want to chat with you until you pass the test.

I'm having trouble finding anything related to this from Google and I tested out 100 texts with a 1% return rate and I thought the message was solid...

We have tested this and used it for all deals.  

As a side note: If the buyers agent came to me and said "We are digging up your yard to do a more in-depth septic test".

Assuming that you have substantial equity with the 12 units, I would expect the simplest play to be:  get an Equity Line of Credit on the current properties and use that to fund the acquisition of a new property (or a few). 

So I decided to do a test and write down the tracking number on each large receipt and follow up. 

We are working on demolishing a property with a couple of materials that tested positive for asbestos, and I can tell you that it is very expensive.