Just saw this post, yes I know the original is 1 yr old.
CloudBerry drive will work but it will be painfully slow unless you have massive bandwidth. They do have backup solution.I have not tried it.
Another option is AWS Storage Gateway. There is a cost of $125.00 /month + S3 storage. We have been using it and it does work well.
See post here: Urbackup to the Cloud
If you have very large amounts of data to backup full backups will take a very long time to sync to S3 unless you have a lot of bandwidth. Currently we are only backing up C: drives for one of our field locations and their file server data drive is a cache drive presented by the gateway so all files are backed up to S3 in real time. C: drive full image backups take about 72 hours over a 10Mb/sec line. We only do these every 30 days and try to stagger the servers. The differentials only take about an hour or so.