While ours wasn't double-wide (in retrospect, it should have been..) it still worked very well. It was as simple as a pivoting front roller with a piece of lexan on the bottom. Flat polybelt drove it off of our conveyor system. The entire pivoting assembly was also tensioned down with some surgical tubing. At first we had trouble gripping the frisbee, but we wrapped a short piece of solid core surgical tubing in the center in a helix and we never had any issues since. Heres some cad and a video:
Videos:
Before the surgical tubing grip
With the grip