It's definitely doable Jenne, but you would really need to do a proper conversion to improve performamce and longevity rather than just putting some gear in it and chucking it off a hill. I have two of these, one will be EDF and one is a spare which I may use for parts or do a PSS conversion on it. Also have a Skunk Works Vamp in the build queue (pic below) - I kinda like Vampires
The Skunk Works guys have their tails hanging out with alot of projects on the go at the mo, so there could be a long lead time in them being able to get another Vampire produced.
Another option is to set the Durafly model up as an EDF or Pusher with a folding prop and just ridge soar it like that. Myself and a couple of flying buddies have had a lot of fun flying working EDF ships as PSS ridge soarers. I have a 4S Skyhawk that is fairly heavy, but goes great as a PSS ship. Having back up power comes in handy if you muck up a landing as it gives you "go around" capability which should limit landing damage. You need a fairly big landing area though. Another thing to consider is what is on your slope, as if you have a big smack up, you could damage the Lipo to the point where it explodes resulting in a certain amount of "deforestation" in the local area.
Some of the things I would do to the Durafly Vampire to do a quick PSS conversion would be:
1) Crack the booms open and insert a large CF rod, then close them back up;
2) Open up the seam all the around the fuse and glass it from the inside with heaps of carbon tow thrown in for good measure;
3) Expoy in a large cf rod into the bottom of the wing from wing tip to wing tip - you may have to stop short of the wing tips o/a the dihederal;
4) Install a ballast box on the cg so you can add various weights for different conditions; and
5) As you are going to make a mess of the bottom of the wing putting in the spar, I would glass the bottom and repaint it.
I did a similar job on this Vampire's sister ship, the Durafly Spitfire and it flies great. Here's a blog entry about the maiden flight: http://www.rcgroups.com/forums/showthread.php?t=1429897