We ran into something similar last month, what we ended up doing is adding the deployed sha1s to dynamodb table, after deployment of a new version we added an i

We ran into something similar last month, what we ended up doing is adding the deployed sha1s to dynamodb table, after deployment of a new version we added an item to the table, after release(complete route53 switch to the new cloudformation stack) update the item and add a timestamp with the release. each item had the following fields: sha1(partition key), environment, deployment timestamp, release timestamp