They know the tenant base, median rents of different areas, how much to increase rent each year, ranges of repair costs (ex: tenant calls and says AC isn't working, no hot water, faucet is leaking, the HVAC system goes out).

- maintenance and repairs (50/month?)

From a “landlording” lens, however, I’d recommend recruiting a solid team of locals (e.g. attorneys, leasing agents, property managers, contractors, etc.) who can help you with closing, leasing, maintenance, repairs, and capex.New construction and turnkey assets are also popular among long-distance investors, since you either won’t have to do much maintenance or capex at the outset (in the case of new construction) or can work with a single, full-service point of contact (in the case of a turnkey property).

Quote from @Justin Brin:  I forgot to mention that the arbitrage renter is a very experience host with good reviews for many years and with a team in place.So if that arbitrager would pay me 25% over what I make with it as a STR, covers all repairs and maintenance, then maybe. 

We always tested people out on small projects first such as doing a gut of a bathroom, 2 day repair jobs, etc. 

I will definitely ask what we can repair, replace and/ or improve as I usually do.

Regarding used mobile homes, you'd have to inspect them to see what issues and/or repairs are needed.

If you feel you need to do an inspection to know around how much cost it will take to rehab, then I would grab a contractor friend for a rough est, and tell your buyer the APPROX repairs needed.

Bought an auto repair shop for 30% of value because of environmental problem.  

The total loan amount for the purchase and rehab can't exceed 75% of the after repair value of the property.