I know if we're truly worried about leaving money in the deal then we should be buying with more conservative margins, I'm not worried about leaving cash in I just want to be more accurate. 

How do I get an accurate estimate / correct credit amount without a plumber physically inspecting the unit , (property is vacant and arranging it to be opened is a big coordinations hassle ; and how much to ask for credit ?

I don't have hard numbers, but even the cheaper price of land may be completely washed out by the fact that a builder in Springfield can buy a platted subdivision for less cost per lot than in a rural town. as a new home builder myself.. the reason most of the mid west smaller areas has little to no production building is as you so accurately point out you can buy an existing home for less than replacement costs.. so until that flips.. the only new construction is usually upper end  those that have the money and want to build themselves a nice home to live in.. as a point in fact. in our market by the time you buy a lot and pay for permits etc your at 200k  before you build anything.. median price point is about 400k.. 

Always price your properties at a realistic and accurate valuation so you attract the right buyers from the start. 

I cant even pull accurate comps on these properties but it happens so often that I am looking for ways to capitalize on the leads.

Theres no way $30-60k is an accurate estimate.

Banking on appreciation is just gambling. 

You should also probably bring a contractor since you probably wont be able to accurately estimate repair costs.

I’m not so sure that the supply/demand dynamics locally are accurately captured in their analysis but only time will tell.

But the MH is now rented and the SFH is now a warm shell and we are now down to finish work - probably two months away from completion.A few weeks ago we contacted our loan officer with questions and to give him more details (he's knew about the plan in general terms since before we bought it) since the finish work (+/- $50k) was planned to be financed with a Hard Money loan and we wanted to make sure our timing was as accurate as possible.Well last night, as you can guess by the post title, our loan officer came back with major issues; saying that "Fannie Mae and Freddie Mac will not loan on a property if it has a MH" - even if the primary home is a regular stick built.