Aside from the $1k difference, I like the "passive" solution of dirt and vapor barrier but I want to make sure it will work.If I'm really lucky, maybe somebody in the Tulsa area could suggest a contractor to do this for me?  

The solution will lie with the city/county planning and zoning dept. who should be able to tell you the required process to get this resolved.  

Ask questions and you'll receive different perspectives, opinions and solutions.

And if you get that far, and the appraisal does not come out, then walk away.The easier solution is to just find another turnkey with better deals.  

This is the prescription phase, where you show the Seller that your service is the best available treatment, taking all the factors of the Seller's situation into consideration for their pain.

This contractor is creative, underbid the job yet still honored their estimate, and came up with solutions I wouldn't have.

Noticed your post and wanted to extend a product idea that our firm has that could be of assistance to your situation, if you haven't found a solution already. 

I have an addendum that names the pet and details their responsibilities including instant repairs, licensing, flea treatment, etc.

We technically couldn't do a thing about it but this tenant wanted her out after a few days but didn't want to be a bad guy about it.Our solution was to pay the downstairs tenant $250.00 to move out within 5 days and this forced the nightmare tenant off our property.

@Dave Toelkes your correct it may be schedule C depending if he is considered a "dealer" in the business of buying and selling option contracts, but the better tax treatment in most case would be for him to be considered an "investor" not a "dealer" if he plans to hold the contract for more than a year and be taxed as capital gains.