Take a page from every sports stadium in the country... instead of launching T-shirts, launch a foam vest of some sort. Clearly you have an issue with hitting

Take a page from every sports stadium in the country... instead of launching T-shirts, launch a foam vest of some sort. Clearly you have an issue with hitting someone in the head with something hard, but probably the bigger issue is launching something that isn't very dense through the air. Quad copter that flies out seems ideal.