It would be nice to have a subsection under the "Item Name" section, that would represent the character's backpack. If toggled all the items in the backpack would be added to the total weight. If untoggled all of the items in the backpack would not be counted towards the total weight. In this manner players could "drop" their backpacks before going into combat and reduce their encumbrance. I realize that many of your players probably do not play the game using encumbrance or that they rules allow for 5-10x ST in pounds to be carried by the PCs, but hopefully there are some players out there, who want a bit more realism and have reduce the max-carry weight to 2 x ST in kg (2.2lbs) which is a more realistic albeit still quite fantastic burden.