Since I'm not buying properties in cash (nor willing to accept a commercial rate for a conventional deal) I am doubtful of deeding property to a Holding LLC after close - it seems risky (and wouldn't that pierce the corporate veil already?).

All institutional lenders, DSCR, conventional and government send out disclosures that are very clear regarding the length of time and the percentages of the prepayment penalties. 

.- Often, a conventional, FHA.

Comparatively a conventional mortgage of $300k @ 6.75% P&I would equal a monthly payment of $1945 with approximately $10,275 TOTAL paid towards principal during the first three years. - Close Cash & Refinance.

@John Mason  you have a conventional second home mortgage?   

So, your 12 months of payments would not be enough to exclude the payment from the sellers debt to income ratio for a future conventional loan.2.

 - financing for ADU addition is typically far worse than conventional Fannie/freddie that would be used if you purchased the property. - the cost starts long before any generated income.  

A DSCR Product is what you are looking for, DSCR Loans aren't based off of your income, they do not report on your personal credit and they are beating conventional investment rates in most cases.

In many cases, the floor between the two is a conventional wood floor- i.e. wood joists, subfloor, and floor with carpet or tile as a walking surface.

It's one thing if you offered cheap crashpads, but if you're trying to attract convention goers, I would think tv is a MUST.