This makes it impossible to accidentally lock themselves out of their room unless they lost their key or made a copy to give someone.

Trying to do that without damaging anything is almost impossible.

It's not impossible, but it requires both patience and the ability to act very quickly when something pops up.  

Any home you purchase will get rented easily due to lack of rentals in all of Sacramento county.It is almost impossible to find a house where the rents will be 1% of the purchase price even with a duplex.

Making it impossible to sell, so they should demo the house and they will buy it cheaply.

Remember that self-managing will be difficult or impossible to scale as your portfolio grows. 

I would probably have a much smaller tenant pool if I did request 2x security +first months, not to say it's impossible though.

Impossible to add any clarity without more detail.You could be buying a 10 million property and net worth is 8 million and maxing out a purchase which could have a higher overall risk factor versus someone with a 50 million net worth and a balanced portfolio. 

Everything seemed impossibly cheap (coming from an unreasonably expensive market), but the rents seem simultaneously too low (to cash flow) and too high (for the ever lowering BHA).

1 - unlikely but not impossible.