If you take the necessary safety measures, there is nothing you have to worry about,

It gives a little more safety to have those students renters, even if it is just a backup renter pool to normal working professionals. 

I’ve always assume the 70% was a safety margin, appraiser having a different opinion, being able to pull out some extra cash to have a profit, whatever...

That would be achieved with a commercial loan trying to keep my cash flow open just as a safety net since this is my first time.

Make sure the properties do not have health or safety violations, no biting dogs, no trampolines, security issues, force place renter insurance, communicate fast with kindness and no discrimination and you won't need a LLC. 

Work together to define a safety net. 6 months is a good place.3.)

San Diego County Covid eviction moratorium allows eviction only on the basis of health and safety. 

Start with your local building and safety department.

They offer levels of safety because they offer other "exit" plans.I agree that The Book on Estimating Rehab Costs, together with the calculator in the tools section can be very helpful. 

That means it could have any number of structural or safety hazards.