If you want to take on additional members down the line, that will also affect your decision.

The SFH is in Irondequoit NY and it seems that the Sewer line is partially blocked.

I sort of dismissed this path thinking it was perhaps along the line of a "loan shark" or a payday advance. 

Your properties sound like they are in decent shape, I’d be willing to bet you have no issues getting the loan.

What about the trend line here in red?

Seller financing will probably be your best bet

As an aside, could it be subdivided where each property would meet current setbacks from front/rear/side lot lines?

A lot of the other numbers they provided seemed a bit out of line from what I would typically expect too, the water testing I’m not familiar with and though I may get some good guidance as to whether the costs seem right or not.

I'll bet 99% would agree with rounding up as a no brainer, effortless way to avoid unintended delays.     

I would also check your comps in rent say go back over the last 5 years and I would bet you are seeing over time increases to your rent in your area due to growth?