Where do you keep the cat litter box?

We have a domed litter box sitting on the back side of the island. We've had our two kittens since 2011 when they were 6 wks. They ride together in a soft-sided crate in the back seat of our truck. They won't eat or drink, just sleep when we're driving, so they are the perfect travel companions.

We also removed a recliner in the rear of the 5th wheel. Then bought a short cat tree that they can sleep on in front of the window when we're parked.