I haven't done it but talked to someone who has. Said he got some of the stick on plastic gutter from Camping World and made a dam around the AC with run-off opening on the side. If it always runs off the front I would check the level on your coach. If the front is low you can recalibrate the sensor to make the front a little higher. I would worry about the dam plugging up and dripping back inside the coach. When I had my Tuscany the condensation always ran off the left side slide topper.
Dave & Myra
One day your life will flash before your eyes,
make sure it's worth watching!