Matt, are you near a 'friendly' auto parts supplier, like Lordco??
You no doubt have seen these plastic add on rain/wind deflectors mounted to/on car or truck side windows
?? Well they also do the same thing when used as a rain gutter on an Egg. Only problem is you may need to buy a set of 4 to get the one you need to fit your trailer. Start by taking the measurement you need for the area you want to cover. It sometimes helps going a couple inches wider, for better coverage, but usually at same price as a smaller sized set. You need to examin the deflector package closely to find a set that has STRAIGHT covers, either for the front or back windows
. These things come in a handful of colors even CHROME and all can be color painted to match the color OR contrast the trailer. A real good feature is they are attached with double sided tape. IF they stay on vehicles at highway speeds, they will remain stuck to your trailer side as well.