Moreover, this tenant does not object should you, the landlord, choose to provide the services of a certified fire inspector in making such a determination. 

I'd think doing so, with full disclosure of your intent to sell the option contract would be less "opaque", and would accomplish the same objective.

In order for actual big expansion, I needed to dip into absentees and hit a higher quantity, during which I still focused on Probate leads separately, and these were still by far better and higher conversions.

Certified mail always help protect YOU.What IF they object?

Large quantity owners and/or large complexes will see economies of scale though. 

Sounds like a headache to me, let the tenant "buy it" and if the deal falls through low ball them... if not find another deal, nothing seems objectively special about this one rather it's emotionally driven.

I think your biggest problem is the unknown quantity of the quality of tenancy.

Also you need to identify the objections or fears she has about investing.  

You've already addressed the major objections with your formula which most investors seek. 

The main objective of the analysis: Do I take the ~$20k and invest into a starter REI property (e.g. 2- or 3-unit for $100k) with the balance contributed to the 401k, or do I contribute all as pre-tax dollars to my 401k?