I personally think it a good area in comparison to other areas in MKE County especially if you are getting a good deal.

You can only accurately determine if the spore count is to high if you have a comparison to go off of, which would be the outside air. 

There is a clear market limit as to how much rent you will be able to charge your tenants.This slide from the Feb 9, 2016 KnoxREIA monthly meeting shows the comparison of the Knoxville MSA to the Nashville MSA (information is from MetroStudy). 

At $340k, it's not going to work and I wouldn't speculate about escalating rents or appreciation - not guaranteed, period...Nashville is very hot right now and the only way someone will make money on this duplex is if they tear it down and rebuild to flip.To give you another comparison, I just put in an offer for a 10 unit in Dickson for $300k - only 45 min's from Nashville.

You can do some comparisons online too.

The incorporation cost are quite minimal in comparison to the cost of acquiring a property and possible exposure you would have personally if things go left.

If I buy the materials I can comparison shop the labor on price/skill.

In Salt Lake house are high in comparison to rents.

I just did a webinar on how to buy in the best markets no matter where you live and in it a did a comparison of the economic and demographic fundamentals of some of the top markets.

I am not saying you cannot do what you propose, but you may need to be careful on the sequence in which you do it.