In the mornings when Annie and I do not have the energy to keep constant tabs on Nate we barricade half of the room, the half with all the things he shouldn't get into, and we let him roam.
Unfortunately, he knows the good stuff is on the other side. One time Annie heard him but could not see him. She took out the camera and went on a search to find him. He was digging a tunnel to the other side and got stuck.