Well, I had one go two weeks in a closet. I think he went into a shed cycle or something, because he didn't make a peep the entire time... and then we woke up one morning and he was hanging out in the living room trying to climb the windows.
I recommend putting out some water bowls for him. Dehydration is the bigger worry.
If you're worried about cold you can buy some extra UTHs and put them in the corners of closets, under beds, and behind bookshelves. That way he has warm places to hide. You can also buy cardboard shipping tubes from your local FedEx or UPS store and cut them up with an X-acto knife, so you've got some cheap hides.
I really like and recommend the talcum powder/flour trick. Once you set up the hides and water bowls, you can sprinkle powder around them to see if he's visiting them. Also sprinkle it along the baseboards and corners, too--they usually stick close to walls and stay behind/under things as much as possible when they cruise.
The talcum powder didn't really help me FIND Morris--as far as I can tell, he simply didn't budge for two weeks. But it did tell me where he'd been... (There was an exit track through the powder coming out of the closet, but none going in. So I think he must have just been in there all along.)