I used to fly the banner tow for our AMA showteam with a 1/4 scale Cub. The banner was about 15 feet long and 1 foot tall. It was an open diagonal mesh material with cloth letters sewn onto it. It has a wooden dowel rod, about 1/4 inch in diameter and 12 inches tall at both ends. The dowel rods have small lead weights on what would be the bottom of the banner to insure that the banner flies right-side-up. The leader is about 15 feet long. I attached it to the bottom of the airplane folded up in a z fold manner and attached with 2 rubber bands that form a V with the top of the V facing forward to provide stability and the bottom of the V aft at the servo release pin. I never had a single failure of the banner causing any issues flight or safety related.