I hate to say it... but once rust works it's way into the gel... it's not coming out.
When I rebuilt the boat in my avatar... there was water sitting in it for a long time, with a few metal things making rusty water. After lightly sanding the surface off, and buffing it back to a shine, soaking it in CLR, letting a paste of "Oxi-Clean" sit on it, and spraying on straight bleach... I gave up on removing the stain, and I put Hydro-Turf on it to hide the stains.
With the above cleaning... the stain was minimized... but it was still there. I don't mean to be a cloud on your bright day... but I spent a week on one stain with out full removal.