Don't pay through the nose for an Extenda Fenda. Mine cost me 90c, made a card board template of the desired shape and size. Using the template I cut out the mudflap out of a 90c black plastic bucket, attach the mudflap with 3 X 4mm aluminium mushroom head Allen screws. Make sure the screws clear the tyre. You don't have to use black, buckets come in various colours. The reason for using a bucket is it is already curved, but you could use anything flat and use a Heat Gun to form it :clap:
Regards Martin.