Almost anything can be insured for the right premium.

Stay out of flood zones, they do not bring a premium and require additional insurance.If you have renovated the house, your expenses should be close to zero for the next 7-10 years.  

Premium ofcourse is the fact that its up and running, undoubtedly.

and what is a good premium range for a four-plex in descent to good shape of 2,800 sq ft?

Prepaids include your daily interest between close and end of month, insurance premium, and possibly taxes.If you take out the prepaids, your closing costs run about 5% of the loan, so not too bad. 

For the bi-monthly, we divide by 2 and add a 5.5% "premium" to the payment.A 5th grader should be able to understand this...which is how I like all of my lease to read.  

So why pay higher premiums for something that is so unlikely to happen.

My friend couldn't even get normal insurance with the tank there and the added insurance would have doubled his annual premium, so that $10k had a ROI that most investors would jump on

We call this concept the risk yield premium.

There needs to be a real premium for the extra hassle of managing so many tenants.