Your numbers should match your intuition and yes, there's only a subset of properties that make sense to buy from an investment perspective.  

I shared proposals among lenders and asked them to lower their fees, match interest rates, and keep third party fees down. 

They're simple to touch up, the wood lasts a long time, if a cabinet door gets broken it's simple to match.

I'm laying the metal roofing sheets across the entire width of the trailers matching the curve of the roof. 

A business can always dissolve but your home is always there so they would likely go after your property. so after you check those two things then check their license number on the state contractors license board and match it with their name then see if they have a bond. that is worth up to $15,000.00 in some states so if there is a case you can always go after their bond but that might still only help a little if there are any real hospital bills.  

And you can paint it to match if desired.

@Dave KansagorLearn their market strategy and see if it matches the market demand.

. - $140-$150 per SF is a pretty good number for a GC to build and you could probably even match these numbers with more generic builders, like HiLine or Simplicity. 

What you are looking for are the micro-markets", that have a profile of "apples", that match the "apples" required by you.

There are websites that specialize in matching the tenant with a prospective landlord.