Window and door sealant?

I was looking at the windows on my camper and noticed that the sealant above the windows is lower than the frame making a trough for water to sit in. I would like to fill this in so water flows over the frame instead of sitting on top of the frame. What is the best stuff to use. The company I work for uses Dymonic caulk to seal up aluminium storefronts but wanted to get some options/opinions. Thanks.