Raise or lower the nose of the trailer a quarter of a bubble so the water goes to the front or back wichever way you prefer it to go (or more if need be). Nothing bad is going to happen. As long as you keep going for perfectly level, nothing is going to change. You've apparently been there, done that; now it's time to try something different.
The front of our Mh is a tad low apparently. We get the white streaks even with the spouts. It seems the water is not falling far enough away from the spout or wind is kicking it back to the surface of the Mh and the rims and tires.
A tube of some sort perhaps 1 inch dia pipe secured to the sides with tape etc when parked. Problems with storing and erecting them of course.
Doesn't seem like to hard a problem just need someone to come up with an innovative pipe or spout extension that isn't ugly as sin and doesn't take an hour to install temporarily and not difficult to store.
I don't have the solution of course.