I suggest running a MySQL slave in EC2 and then exporting the data from the slave:
http://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/MySQL.Procedural.Exporting.NonRDSRepl.html
I recommend checking into Percona's XtraBackup.
https://www.percona.com/doc/percona-xtrabackup/2.1/how-tos.html
One workflow I can see is
RDS -> EC2 MySQL Slave -> Xtrabackup -> BareOS Normal File Backups
This give you many recovery options in case of RDS issues. We don't have this in production yet, but something we are considering.
Using xtrabackup allows us to store backups locally on an EBS Volume. We can then snapshot that volume as needed or even move it to another region.
We will then use bareos external to AWS for last-ditch recovery efforts.