So now I have a whole different issue to deal with.

Most rooms in America are about 100 sq ft but it may be different there. 

Thank you, Doing work for an investor is different then working on a 203K loan. 

I am in a different niche we don’t do partial or fractional interests  

We have 7 units across 3 different properties.

I'd send out 500 at a time, using a different mailer/method weekly.

The collateral makes a difference.2. 

Although whichever option you go with make sure you're also thinking about the long-term property value and what makes the most sense vs trying different angles now that negatively impact future resale/property values down the line. 

Connecting with local GC groups in your area will help you connect with subcontractors, find out tips and tricks of the trade in your local area (since all areas and their real estate differ slightly).Also, have you considered the motivation behind building a brand-new duplex versus finding one on the market?

Rent in the neighborhood is $895 for a 2 bedroom, 1 and 1/2 bathroom, so for 4 units it will total up to $3,580 ($1,073 difference).