Thank you Kevin. I used a slightly modified version of your approach. I ended up making the trail using the pen tool with a fill instead of a stroke. I then created a square that I used as a track matte on the arrow trail. I animated the positions so it follows the arrow head.
The curves of the arrow trail aren’t quite perfect, but for a local commercial that won’t air for more than a few months, it should work.
Thanks to everyone for the suggestions!