Crating / confining in the bathroom for a time, all should help. A small area with the box and I agree with Laura's suggestion too, put some of HIS stuff in there.

Make sure he can jump in and out of it. At 5 weeks, he "may" be too little to get in some of them. Depends which type you have. Leaping OUT is always easier, lol.

When I was doing the rescue work, we kept the small ones in a large crate and used a Cool Whip container as a litter box, so they could climb UP and in, as the young ones love to climb. Heck, the adults do too, but for different reasons, ha ha.

What a handsome gray / white boy! He is so lucky Dave stopped to investigate!