If you only plan to rent so little during the year and aren't bothered by the costs (which may be deductible as a business expense) go with whatever insurance the car rental company offers. Yes, it is a revenue generating source and so forth but if you are all worried about liability and cost due to an accident it is the easiest way for you to go. Beauty of taking such insurance is if the vehicle is damaged you simply sign a few papers and walk away (in most all instances). Nothing goes to your insurance company and or your record.

Non-owners insurance is mainly for persons who rent and or drive vehicles they do not own on a daily or very frequent basis. Taxi and limo drivers who do not own their own cars but work for a company come to mind.