I know out of state that manage their property, so it's doable.

A fast flip is certainly doable as we have situations where housing prices are being bid up over asking.  

So long as the holding costs to get there are doable, then I should find a way to move forward.

How doable is this in the Atlanta market?

It is certainly doable in the Greater Atlanta market. 

Tina Huffman that is doable throughout the county.

Is that doable?

If all that is doable, it would be cool to do park models.

But I'm planning for income from quality debt-free real estate to be maybe 5% (this is a doable cap rate in desirable markets).This is not the best "return" I can get, but when I optimize for income, the best return is not my focus.So, in my humble opinion, the trick is to focus on overall return (best achieved by focusing on getting more equity using leverage) with an eye on when you want to focus on income. 

You would have to be super creative to get regular monthly cash flow out of tax liens (It is doable and I have ideas, but it would be a weird proposition).