Ziggi,
I have a 2001 Outback with the a rear storage locker, not sure if it's similar to yours. I cut a short section of PVC with an angle on one end, and flat on the other to use as a prop rod. Glue a piece of foam rubber to the flat end so it doesn't scratch the lip of the compartment, and you're good to go! I keep mine in the locker, and use it when I'm changing out skis or letting the carpet back there dry out. What length you use and the angle needed to line up with the lid depends on how far you want it to stay open. I put a bolt on the underside of the lid, off to one side for the prop rod to hold on to....otherwise it will slip off. It needs to be on one side or the other for easy access. If you're gonna prop it up for any length of time to dry out or whatever, prop it up in the middle, with the lid fairly high up. This will help avoid any warpage.
Brian
You're never too old to be immature.