And another draw-back to this part of Idaho, is that due to low wages, rents on anything here, do not exceed a certain thresh-hold, except in rare instances.

Make sure to get real estimates on getting it to fair, good, and great condition -- and then evaluate the rental value and ARV of each option.One final consideration: Like many markets, Memphis has some decent areas and some bad ones, and super cash flow often comes with drawbacks.

If not that may be the drawback. 

However, with a management company you can trust, these are some of the biggest drawbacks you should ever have to deal with after buying properties out of state.For Fort Myers, I can highly recommend Royal Palm Property Management.It looks like there may be a few expenses you've left out, but your calculations are correct.

What is the drawback to hire regular SFR property management (instead of onsite)  to manage the park, and pay them a % of lot rent (all TOH homes in park)..? 

It doesn't account for different goals...for instance, paying off rentals would provide stability, peace of mind, higher cashflow, something tangible to pass on when I die, and a myriad of other benefits (yes, I know, with a myriad of drawbacks too).  

What are the drawbacks?

It’s renting for 600$ monthly till 11/2020.. draw back is it’s high crime.

Are their drawbacks to doing this?

[Beware = https://www.biggerpockets.com/renewsblog/house-hacking-drawbacks/]I would look for a 2-4 unit too house hack.