There are two things I can suggest to you since I know soldiers have taken those toys to the desert....
First....a piece of clear masking tape over the screen will let the tape get scratched instead of your screen...
Second...if you go to Gamestop.com or the store or Babbages they sell kits to go with the Nintendo DS it comes with charger...earbuds...and a screen protector I believe it is either $9.99 or $19.99
But that is what worked out in the desert and war of Iraq so I am guessing it will work like a charm for you here...best of luck to you...