It's very easy to BUY a house, but 100% financing can produce high monthly payments an de make it difficult to cash flow.But, you're getting a duplex, so you may be doing just fine.

Now this is when it becomes a little difficult I’m trying to get approved for FHA Loan with the 3.5% down and it comes down to my credit being a little beat up I have enough for the down payment and Income to debt ratio is pretty high.

If it averages $50 a month, reduce the rent for Tenant A by $25 and increase the rent for Tenant B by $25.

Most of the time, people who get a raise/second job or more income from any source, wind up increasing their spending and up their standard of living and never actually use that money to pay debts off.

As you scale your business it will become increasingly more difficult to allocate your expenses to the proper rental or business if expenses are running through your personal account.  

Is this something really difficult to do while living a great distance away?

My question is as the new owner, does that lease still have to be honored by me or can I redraft a lease (with a lot of the same stipulations) but giving them 60 days notice of a increase in rent?

You would be better off to shop for a new manager to increase the income from the property prior to the sale.

They keep you busy at the refinery with all those "unplanned flaring events"...I've lived in Hermosa/Redondo/Torrance the past twenty years and finding something affordable is pretty difficult in our area. 

Having said, it depends on what your strategy is.If you implement the BRRRR strategy (look it up if you are unsure what is), you can get that type of return.But if you are looking for a  turnkey property to rent out, it will be very difficult to get a 15% CoC return in my opinion.