Kayak molded foot rest padding

I have a 15+ year old OK Drifter with molded foot rests. I am fairly large and use the furthest foot rest position. When I extend my legs they press into the molded ridges for the shorter foot rests. This can make my legs sore. Has anyone found a way to pad the molded ridges or better yet fill in the gaps to present a smooth surface to rest my legs on? I would not be able to make permanent mods to the foot rests as my grandson uses the Kayak also. He is 9 and has a ways to go to catch up to grandpa.