See if there is a propane wholesaler near you who can inspect and recertify them. Depending on your area, this may be possible. I can get 5-year recertification on my tanks and I have two that are more than five years beyond the original 12-year expiration (one tank is 19 years old, the other is 22). It comes down to the valve type generally, the older type won't get a recert due to safety reasons but newer valve types can be as long as the tank is in good shape and doesn't currently leak.
“See if there is a propane wholesaler near you who can inspect and recertify them.”
I checked again and the nearest recertifier is 50 miles away. I could buy new tanks for not too much but, as I said, I just want emergency propane. Maybe I’ll throw them away or cut them in half and use the bottom halves for a planters.