[JimD]

I don't know why you think that the fasteners would not "have anything to bit into" if removed. They will bit into the same thing they are right now. If you don't remove the fasteners in the area the mud flaps seat to then the flaps will stick out a little because they are going over top. You could hold them in position that way and see if you like it. I didn't.

It's been awhile since I did this but I think in the back most, possibly all, the fasteners are screws. In the front there is a big plastic screw you will not want to go over and some push pins. I think in all cases, it's best just to remove the fastener, seat the mud flap, and reinstall the fastener.

Jim