If their policy ever lapses or is canceled, they are automatically enrolled in my master policy and covered. 

The main factor is will rents cover the debt liability and can you sustain 3-4 months of no income to cover the debt? 

STR management is 20-25% (I would recommend self managing or getting a VA), since income is higher you could probably get away with 5% for maintenance / cap ex but remember you need to cover utilities and cleaning for these units which drives up costs.

To get a full picture, there are many, many questions you need to know the answer to, and this is only a partial list.

Getting into the house and house hacking at the very least (when done correctly) puts you in a better position to save more aggressively especially if your entire housing payment is covered.

@Mohit Gupta  depending on number of occupants your regular insurance can cover it, read the policy, ours covers two roomers. 

@Robert Quiroz, I know this is fairly well covered at this point, but I align with Robert...  

If they are taking out a few breakers and a fire happens insurance will typically not cover anything.

The 4 guests smoked marijuana in the house (strong smell), broke a window blind and a picture, put a hole in the bathroom wall, chipped an end table and worst of all vomited on the couch and front porch.

A good rule of thumb is to keep 3-6 months of operating expenses in your rental account as a cushion.Once you’ve got that covered, you can start investing the excess.