a vapor barrier is a must behind the lap siding

I used to have difficulty in California converting garages because of the lack of Steel/Concrete PSI/vapor barrier.

Garages are not built as living space, the main consideration being the slab and it's lack of proper rebar, PSI, and vapor barrier.I've been asked to have the slab X-Rayed to prove that it was up to current codes.

Accept her late payment for June, along with all late fee, and court fee (for filing eviction), and withdraw eviction, and suffer again with her being late again and again?  

You could yes, because Tyvek is breathable and not considered a vapor barrier. 

We get along really well, so I'm not concerned about her being a tenant, and I'd be happy for her and our kids to have a safe, secure place going forward.

FYI: The repair work is crawlspace/vapor barrier/sump pump/dehumidifier and outside drainage along the house and hurricane windows.If I form an LLC, will I need to re-finance with a business loan?

If needed, add a crawl french drain, sump pump and 6 mil vapor barrier. 

Principal risk is vapor intrusion (vapors from groundwater migrating into buildings) or contaminated groundwater if used onsite.

My wife is thinking to put a plastic vapor barrier over the dirt floor and to cover with rubber mats?