This home sounds like a natural fit for a rent by room concept or PadSplit! 

A lot of times even if you can get the smell out it will leave permanent dark spots so you'll need to use a dark stain instead of natural wood.

You’d naturally want to charge more.  

Certain types of glue can outgass smell like natural gas for weeks causing nauseating and vocal complaints.

Fifth, elements outside your planning or control can increase expenses significantly; tax increases due to budgetary shortfalls, insurance costs doubling due to natural disasters, tenant damage beyond what the security deposit will cover.  

On the other hand, natural hardwood floors are beautiful!

Some plumbers refuse to install the cheap water heaters, so they will naturally cost more.

Not necessarily a deal killer IMOAlthough it's against nature, the tree can be removed, the roots poisoned and there should be no damage to the foundation long term.Just my opinion 👍

This is the nature of the business, you are not doing anything wrong from what I am seeing.

Quote from @Bill Brandt: thanks for the clarification, the parcels being sold are "better than average" the parcels being sold are on a private lane,  with mountain views,  have natural gas,  electric, fiber internet, and cell phone service available.