I bet I can even guess who the property manager who let you down was...

Because investing is now popular / trendy, and this property in particular will have higher demand, I'm willing to bet that it goes for well above list price.I applaud your thinking and analysis though. 

You can take it up another level and if you end up in a place where you have a modestly sized 2BR you can find a roommate and have them pay half the market rent for the unit and split the utilities and then you could be in the living free/making a small profit area there.

Verify that the reference list is estimated close to the size and type of your portfolio. 

My building has substantial upside on the rents and the lot size is substantially larger.

That's somewhere between 1% and 1.5% depending on the overall project size.

The problem will be that if she only qualifies for a 2 bedroom unit based on her family size, then the most the Housing Authority will pay is whatever Fair Market Rent is for a 2 bedroom. 

We asked him to confirm the size of the house.

Your best bet is to find a local investor-friendly mortgage broker and ask them what they are seeing in your market at the moment.  

Don't listen to the negative thoughts in your head about your age, experience, shoe size, eye color, etc.....Just Do It!