I have a gregory pack, both the side pockets on my pack are mad of elastic and are therefore too tight to fit a nalgene. this wasnt a problem until i got trekking poles and can no longer carry the nalgene in my hand. i want to make one of the pockets on the side bigger so i can fit my nalgene in it. i know some will say use a camelbak but i dont like em for a number of reasons. can anyone give me some advice on altering the pocket? i can post pictures of my pack if that would help.