You would have no problem painting fenders or a rack. Any plastic fender like Planet Bike or SKS can be painted. Even Honjo's can be painted look at Chris King bikes with his painted fenders. Scuff up the plastic with sandpaper and use the right spray paint. You need a paint that is flexible, for example a paint that can be used on plastic lawn furniture, maybe Krylon. Same with the rear rack, make sure it is clean and use something like Tremclad or Rustoleum and spray paint away. I would think the rack might take a beating and have the paint chip off when using it, but all you would have to do is take it off and do it again, you will have already bought the paint. As for what racks, well I am partial to the Axiom line of racks but there are so many out there, it is not hard to choose.