Yes, that would be the pertinent thing to do and in the future, should I ever rent a car again, I will make sure to do that. I rented a car from Isis a few months ago and Margarita and her husband were very forthcoming about their insurance policy. They showed me the policy and even spelled out the specific coverage.
I believe the US Consulate on Cozumel issued a comment back in April regarding the insurance that rental car agencies are required to have. Her advice was to ask to see the rental agency's 3rd party insurance policy at the time the car was rented. If they refused to show it to you then they are in violation of the law and you should find another place to rent a car.
BTW, I have now learned that this information is required by law to be spelled out specifically on the rental policy. There should be a paragraph that spells out how much the insurance coverage is and and space to write in how much the person is paying for insurance, the daily amount of insurance coverage and the amount of the deductible. (At least that is the way it was explained it to me.)
Looking at my receipts from 3 previous car rentals from Less Pay, I can see that these were never filled in and the amounts were left blank on all three contracts. Whether they accidentally omitted this or what, it was my responsibility to know how the contract should be filled out. I won't make that mistake again.
Also, since I was a passenger, I would not have had access to their insurance policy but they should have provided it upon request.