The simplest fix is to park on a gradient such that water flows mostly to the back of the camper.
Another option, to expound on what was previously posted about caulk, is that you can grab the garden hose and run water down off the front of the camper. You need to see the normal water path to determine how to divert the flow. After you see the flow path, it is up to your own creativity as to how to divert it as the options are only limited by your imagination and the materials you can get your hands on.
