I have never known or had a single one done legally where any financial institute called a DOS for such, not 1 ever. 

Yes it's definitely legal, and I've sold a few this way.

Or for the high-end primary homeowner has no legal way to 1031 exchange; so the deferred sales trust is a no brainer.

There is nothing about how long you need to occupy the property for.So unless our lender puts a demand on us I see no problems legally in occupying each property for any amount of time to fulfill the requirement, then rinse and repeating this process up to our full entitlements, so long as the lender is willing to keep giving us loans.

I use this for tax and insurance which all properties have)Expenses (general business like admin/legal and by unit for repairs, trash, utilities...)EBITDA (earnings before interest/taxes/depreciation/amortization.

The buy back was a comment over the phone, nothing legally binding unfortunately.

I'm not a financial lender or whatever the legal term is. 

I also understand accounting and legality may play a role.

Good news is our land is where all of the next-door houses are (free houses, I think legal issues). 

Hire a company/person that is solely a QI like @Dave Foster they do it every day and will keep you legal and on track.