You'll essentially be a holdover tenant if you don't leave on the previously agreed upon date, so the reality is you could get into legal trouble because they could pursue an eviction and other monetary damages against you.

I would look in basement for any signs of old piping or holes leading out that way to give clues of any tank installed in that area. 

If the property has any issues that would cause someone to not be able to live there (roof, plumbing, broken windows, holes in the walls, etc.) those items would come back subject to repair on an appraisal and need to be fixed before you can get any type of mortgage financing.

I'm hoping these properties to fall in a C class neighborhood...looking to avoid bullet holes and "war zones".  

Doesn't necessarily need to be something monetary but even the possibility of hiring them for your properties could be value.After a couple times of doing these, you'll have a better understanding of the process... but there will still be variables (labor, materials, your exit strategy also carries weight as well, whether you're going to fix-and-flip to a retail buyer or rent it out.)

We also have a construction manager who will be providing GC services free of charge for the actual rehab part of the job (our monetary investment to fund all construction costs, he will be providing general labor and management).

I still think HOA or County law might trump this loop hole..

My 'honey hole' as Jay likes to call it is 30 mins out and requires me to have a good maintenance guy on-site, in country.

Problem is I'm being told that Umbrella policies have loop-holes and even LLC protection can be broken. 

Liquor bottles everywhere, dog crap, holes in walls...