There are a lot of good tools out there
At least wait until Cloudformation/Terraform supports it
DynamoDB backup is still not easy, there is no out-of-the-box backup solution
The truth is: it has a higher chance to lose an important service in a whole region (S3, Dynamo, Kinesis), than losing an AZ.
If you want better SLA than AWS, go multi-region from the beginning.
It can be hard to change it later