If anyone is interested we updated our RDS service broker to support deploying a new DB instance from an existing DB snapshot. The main use case here was really to be able to have some prepopulated databases for projects as well as to easily make a copies of databases between environments with having to engage operations less. Currently you still need to get the snapshot name from a system operator but after that you can provision from snapshot.

https://github.com/epoelke/rds-service-broker/tree/v3