Assuming no cash fordown-payment, I'm leaning toward using the HELOC for 20% down and using option 3for a 30-year mortgage at 3.75% to keep monthly costs as low as possible and maximise cashflow. 

You are obviously a ultra conservative individual and for that reason will not be able to maximise your returns.

If you are not willing to pull the equity you should seriously consider selling and redistribute your equity to maximise your returns.

If the planets align as I hope I will likely be based around the Plano area (main job, easy routes to airport), but setting up some alerts with some key words is a good call @Sol N.To be honest, until recently I hadn't considered real estate as a real investment, more of a place to live, but after looking at some of the material here I'm beginning to incline towards the multi-family (2plex, 3plex, 4plex) unit-type approach to maximise initial investment, and take advantage of any tax breaks whether now or down the road.

S8 is a viable option for hobby landlords that are not concerned with maximising returns on their investment.

If you want a house with character leave it as it is, maybe your contractor will buy it, but if your goal is to maximise rental income do what you plan and change the lay out.

It is obvious (to me) that you cannot represent certain Clients objectively any more, but have joined the "I will work for you as long as you know that I will not hesitate to go behind your back if necessary because my ONLY goal is to maximise MY income" brigade (ie. you should now recognise that you have no business pretending to answer to a "higher standard" of ethics any more).

Second if she can afford full market you have maximised your returns as opposed to subsidising your tenants rent.If you do not put it directly to full market, and she can not afford full market, what you have accomplished is to lose money and end up with the same vacancy in the future that you are trying to avoid.

Hello,I'm looking to buy out of state rental properties, either single family homes or commercial, and was wondering what cities I should consider if my goal is to maximise ROI.

Ensuring my time here on earth is well spent and maximise my potential every single day.