The neighbor next door also had a myriad of cars, vans and portable garages in his front yard that had me thinking it could be an issue when selling tilm came.

get a portable scanner.  

You may have to start off Dry Camping or find creative ways to supply things like water(portable water tower), Electricity (solar farm), etc.I wish you the best on your journey.

Dodd-Frank may be applicable selling to a consumer, if it's portable it can fall under the mobile home guidelines.And yes, if its a residence TREC applies. 

Where/How do i find the best portable storage containers? 

The portable alarms that home depot/lowe's have are great.

The "portable" or Micro units that Trachte makes would likely get you past any setback issues but they will cost a bit more...probably $300,000 for the same square footage.

OR, get yourself a portable hard-drive and save those files on it and put the hard-drive in a lock box or safe at home. 

I would tell them it is what it is and they are welcome to supplement the air conditioner with portable A/C or window units.

I once sold a house years ago that had equity in it to an investor.The seller was in financial hard times.The house was paid off but then used a loan from a predatory lender who was now trying to foreclose.So I listed for them with plenty of equity left.The seller ended up selling and still getting 15,000 from the sale.The lady had a few cats and then took in strays.The cats started breeding and then more cats showed up under the crawl space where the vent cover was broken and they would go in and out.There was at one point before I listed it 55 cats in there.Animal control came out and got 48 cats out,3 were dead,and 4 were too wild and ran out of the house.She kept most of them in one room and a few in the living room.I tried to help her by cleaning the room and used every cleaner imaginable.I don't care what people say about cleaners they don't work.The only time is if it's just a few place and the carpet pad and subfloor isn't soaked or they sprayed on the wall but not in the corner.If the urine gets under the baseboard or in the corner forget it.You will have to tear out the sheetrock in that area and clean behind it.For subfloor depending on how deep it has penetrated the wood you can sand the top surface off to get rid of the smell.If it's deep you have to rip the subfloor up and replace.What you need to do is take a portable black light and walk around every area inside of the house and outside to see where the marking has occurred.It it's simply the walls and not the floor or corner you can clean easily.You will know by the black light how extensive it is.