I'm ok with this for a bug fix.
Here's more for the more complete issue:
it looks like alestic and rightscale images mount the first ephemeral disk onto /mnt. According to the amazon linux guide:
"The ephemeral drive ephemeral0 is mounted in /media/ephmeral0 only on S3 backed AMIs."
When we address this holistically, we may need to have a script that arranges the fstab and formats volumes accordingly, possibly using lvm or something to span disks together. Then, we can have a clear mount setup that whirr is authoritative for.