The other thing too - even if your husband's insurance would take you on without a UK licence, does his insurance even cover car hire in the US? Ours doesn't.
If you still have a legitimately legal US residence, you could try taking out a trip-specific policy through this company:
Access AmericaThey partner with the online booking website, Orbitz, so normally if you are booking a rental car through the Orbitz site, you will get the option to purchase this car rental insurance at the time of your booking. You can download a copy of the policy & you're good to go. (Most states require that you carry your driver's license as well as proof of insurance in the car with you, so downloading the policy is important, IMO.) It does work out cheaper than getting the expensive add-on insurance at the car rental counter when you are picking up the car.
I have used it previously when I still could count a legal address in the US, but alas I can no longer do that.
There might be other similar companies too, but I am not aware of them.