Ordered the filler cushion from the factory with my '06 Outback. Have not found it to fall through the mounts at all. It fits really snug in my boat, and love the option. I also bought the jumpseat which was a great purchase for us. Usually we sit it in the bow walkthrough, or else right behind the driver's seat facing aft. Another good option I am glad I ordered. Check out my webshots page, I think I have pictures on there of the interior.

oh yeah, prices were: $174.00 for the bow cushion, and $271.44 for the jumpseat.

http://family.webshots.com/album/556372222YmuvBl