I purchased a telescoping tiller extension to be able to move forward on the boat. I only use it during light and medium air. I have a clip to hold it to the cross bar and don't use it during heavy air, because you have to sit as far back as possible to keep the bows up.
I have a mild love/hate thing going on with my rudder setup. In heavy air I like the fact that is behind the main sheet because I can get farther back on the hulls and push the boat harder. However when the air is medium/light you have to swing the tiller around behind the main when tacking or jibing. Most Cats are like this, but I used to own a cat with the cross member forward of the main sheet and prefer it that way.
The tiller is not class legal, so if you are going to race, you'll have to remove it.
One additional item you might want to consider is a traveler for the main sheet. Not class legal for racing but really helps with sailing off the wind.