HMM , I use the prolight full length pad. I never thought of putting the pack under my feet. My g4 has a double thickness closed cell pad reinforced with internal horshoe arrow shaft. If i could stay ontop of them both a short pad mightwork! I know I can definatly tell if my feet shift off of the long pad on a cold night. pehaps a lite velcro stip to attack short pad to my g4 back support would make a good full lenght pad. I can see the ounces falling. Thanks