Dirt, water and leaves were being sprayed up by the Firefly wheel. Especially the wheelchair's flip-back footrest mechanism was catching a lot of wet debris. The picture shows some of the schmutz after it dried (a lot already fell off and made a mess at home).
So I super-glued and taped a rubber sheet (cut to L x W: 5.25" x 5", 1/16" thick) to the fender. The mudflap is effective, and after many trips with plenty of wet leaves, nothing new has stuck to the footplate. It reduces the open tire aperture to less than 1 inch from about 3.5 inches. Because the material is flexible, ground-contact is not a problem. In the photo, the bottom of the tape (2" wide Polyken) corresponds to the fender bottom.
2/19/2019 Update: The link at the top shows pictures with a mudflap. So the manufacturer has either added one since mine was made, or removed it since the photos were taken.
