Well I've been around some banner towing with the full scale stuff, so I'll offer a few thoughts about them that might be useful here...

Bax is right about the leading edge of the banner needing to be stiff and that's where the weight is as well, I've never seen one weighted at the back of the banner.

Full scale stuff is set up so the banner attach mechanism is at the rear of the aircraft much like it is with airplanes setup to tow gliders.

Full scales do not take off with the banner attached, but a line with a grappling hook is attached to the aircraft then run into the cockpit area. The banner is laid out so the front of the banner is facing rearward down the runway with it's tow lead laid out farther down. After takeoff that line attached to the aircraft is dropped outside trailing behind and below the airplane, then they make a low pass over the runway where the banner line is supported across the runway on two poles about 12 feet high and sixty feet apart. The pilot then makes a full power "best angle of climb speed" pull up and if he caught the banner it follows him.

These operations require an aircraft with power to spare and even then overheating can be a problem. There also must be some modifications to the tail of the aircraft to take the additional load as well as the ability to release the cable from the cockpit, usually just a cable with a T-handle is used on the ones I've seen.