This will help you build a reputation and a following.

Build trust and reputation.

Definitely speak with a reputable real estate attorney, regardless of how you mange to secure the mortgage.

Your duplex will appraise the same as any other stick built duplex, it'll insure the same, etc. it is NOT a mobile/manufactured home, but you're going to have your construction loan for a lot shorter period of time which means less interest you pay and the faster you get in a tenant and start that cash flow.Importantly.. you should come in WAY below a $250 sqft price.. here in Houston I have a modular builder that starts at $88 sqft and with the improvements i am requesting just about hits $100.

@Marco Morkous - I would first call a reputable plumber to run a camera down the main line, and if all clear, then your issue is from the city sewer main.

Preferably from a reputable real estate investor who focuses mostly or entirely on fix and flips.

Can I just find a reputable agent from here and tell them what property I'm interested in? 

You don’t have to go out and find reputable vendors, your property manager has already done the work for you. 

I would not want to jeopardize others' reputation.

So please refer me to reputable contractors or if you are a contractor please DM me.