Camp Dry Works awsome on the outside! But for what you are describing non of the spray on water repellers will prevent the water dripping. The insullation is the only way to seperated the tempature differences that causes condensation and results in the dripping water. If you are talking about a flip style shack set it up and think about how to atach it to the tubes, duct tape, tarp tape, gorilla tape, gorilla glue....... This will solve your drip issue! Don't try to attach it to the fabric.