What you are looking for already exists. DAR
. I searched for 4 years for something to give me backups my way. I found it in DAR.
Once you get the config worked out (takes a bit of study and practice), you will have a backup in which each file is compressed individually. Dar allows you to specify files to exclude from compression (because they're already compressed); directories to backup the tree, but leave out the files; directories in include/exclude; the list goes on.
Restoration is easy, and works like a charm.
My 6 gig setup ends up as 2.7 gig in the backup file.
Dar is command-line. The GUI version is Kdar.