I read and do keep my show birds strictly inside with a clean coop. You could also use wire cages. I wouldn't because that just doesn't seem enjoyable for the feet. My birds leg feathers aren't in the greatest condition due to leg mites. Another reason why not to let them outside is the sun will bleach their feathers. The judges definetly do not like that.
First you want to grow the actual feathers out on your birds, don't let them get damaged by roosters mounting hens or from the mud or too much sun. About a month before the show I like to cage my birds and make sure they are cage trained to pose when people are around.
Second you'll need gain a lot of field practice on bathing your birds, since the week or so before your show you'll repeat the process. The feathers shouldn't get fecal matter or excessive dirt, they can act like normal chickens but don't let them get too into being a real chicken...if that makes sense.