WordPress FTP Upload, Amazon S3

[ Moderator note: moved to Fixing WordPress. ]

Hi,
I’m searching for a solution for users that are registered to my website and want to upload big files using FTP and I need some advice.

Now users upload by using the front-end and the files go directly to my Amazon S3 bucket using a plugin. Each user see his own stuff only.

Possible solutions:
1. I create manually a FTP user + custom directory and give him the user/password. Also the user must see only a specific directory when using FTP.

2. There is a plugin that allow me to assign the uploaded files from a specific directory to an user? Or even to send them to Amazon S3?

Thank you!