Also, in the event of major damage, usually 50% or more, you have to rebuild to Current zoning. 

Payment processing fees, marketing fees, hosting fees, lack of host protection with damage incurred by guests, etc so these additional costs need to be accounted for when running numbers.

For example, if I could use my phone to take a picture of a damaged AC and the app pulls up prices in my area?

But in those better areas most of the turnover costs is just tenant damage and wear and tear which you will have anyway.That style of floor plan could be under a hundred K to build but watch the quality.So unless your build quality is high to justify the high total cost why not buy existing and just move the lots at a profit?

You have to budget for damage and replacement of those items. 

Always keep in the back of your mind that the cost of a vacancy is miniscule compared to the cost of a eviction combined with intentional tenant damage.  

These entities, when created and managed correctly, can and do compartmentalize the damage from a law suit. 

If someone else caused the damage, she can coordinate having that person pay for the damage ect… 

That's why we also have a simple early termination for leases (1 month + deposit if there's no damages), because they get to walk clean and we get the property back, no fuss no muss.

Having the GF on the lease also protects the tenant, in that if the GF goes crazy and damages stuff, it's GF responsibility, not the tenant's.