So here is the "cat tent" I made for Spike.  He used to stay under the couch the whole time we are underway, but since we installed the inverter under there he doesn't like it as much.  Therefore he has come to lay in the covered litter box.  That's why I thought he might like this tent.  He has only been in it if I force him, or put treats in it.  He has also started laying behind the forward toilet while underway.  So I put the tent right next to him, but it didn't help.