Removing document overhead from audit space useage

I have a series of 10 40 page brochures with a small image on the cover and mostly text inside that I want to post on a website or users to download. Each file is around 13-15mb. This seems really large for a simple document so I ran it through Audit Space Useage and found out approx 92% of each document was document overhead.

Using the optimizer, I tried a few options and discard private data of other applications and discard document information and metadata. I managed to get the file size down to 500kb but all my links were removed (cross references and hyperlinks to web and email addresses).

Is there a way to remove document overhead (some or all) but still retain link information?