Dont ever use silicone http://www.campercommunity.com/forum/#around camper windows, or on rubber roofs, etc... It simply does not stop water leaks. I recommend using eternabond for rubber roofs, and you can buy replacement window puddy to seal your windows. Been there done that. My camper was covered with silicone when I bought it, roof, windows, etc.. I think that is why they sold it, it was still leaking until I removed it all, and fixed it correctly.