Get an umbrella liability policy to cover concerns about liability and if you want to explore it, there are land trusts that you may consider. 

I have one small park (1 SFR home and 4 tenant owned mobile homes) and am in escrow on a medium sized park (9 tenant owned homes and 25 unoccupied lots)My thought was to have an umbrella general liability policy covering the business and a separate policy for each park, as I buy more.

I think it's easier to have an umbrella liability policy for all the properties. 

However, I am looking for liability insurance/umbrella for the whole flipping business.

In my case the mortgage closed prior to their required date in 2016, and is 4 years old already, so I am not eligible for transfer.So is my only other option here on the mortgage in question (a rental) to either just shoot for the umbrella insurance policy, or to refinance out to either a commercial loan or some other loan option? 

@Chris Allen, if you want to be thorough, make sure to account for the following expenses:1) Mortgage2) Mortgage insurance (PMI or MIP) or FHA Risk base3) Property Taxes4) City Taxes5) HOA (Home Owner’s Association) Dues and Fees and Assessments6) Insurance  a) Property Hazard Insurance (0.3-0.45%)  b) Flood Insurance  c) Earthquake Insurance  d) Umbrella Insurance7) Vacancy Rate (usually 8% - the equivalent to one month a year, or 5-6% if multifamily and/or if experienced, if not use 8%)8) Utilities (you’ll have these if your tenant is not covering them and/or during vacancy)  a) Water § Sewer § Garbage  b) Electricity  c) Natural Gas  d) Propane9) General Maintenance (usually 5%)  a) Upkeep § Landscaping  b) Snow removal  c) Repairs  d) New Appliances  e) Make ready10) Capital Expenditures (usually 5%, higher is the property is old and obsolete, less if fully rehabbed and all mechanicals and roof are new)11) Property Management (8%, even if you self manage, your time still has value and there might be a time when you'll want to be completely hands off or you'll not be able to do it, vacation, retirement, etc.), including...  

I did some research and my real estate attorney confirmed that I should look into an umbrella insurance policy.

I have an umbrella and I watch the forecast and the sky.  

My insurance company quoted me a $1M umbrella policy over 4 properties for about $400/yr. 

@Brett Palmer  Umbrella insurance is a great start