I have a non-owner policy with USAA which covers both of us for $25/yr. We probably drive about 30 days a year.
Seriously? That's an awesome deal. Aside from calling USAA, is there any additional detail you can provide.
I've been car-less for over 10 years and have looked into this matter a couple of times. My experience is that this type of insurance is very rare. I called a handful of companies and they basically blew me off. The last time I checked was a few years ago so perhaps things have changed.
I rent about 15-20 days total annually (for personal use) and I just pay the daily rate for liability.
This varies hugely by state. My quote from USAA was more than 10 times higher. Your best bet is to just call.
The first year, about 2010, it was only $5/yr so it has gone up a lot. (Generally USAA insurance coverage and service has plunged while rates have risen the last several years.)
Ours is cheap as we live outside the US:
"This policy provides coverage within the policy territory of the U.S., its
territories and possessions, Puerto Rico and Canada. See Part E - General
Provisions. It is designed for members who live outside the policy
territory and occasionally rent or borrow a vehicle for use in the policy
territory. No coverage is provided for persons who reside primarily in the
policy territory. If you move to a location within the policy territory,
please contact us so we may ensure you have appropriate coverage."