You are already in some trouble at step one - how do you figure out if something has any of those feelings? Just asking or observing the behavior does not seem good enough, one can easily write a program that prints »Yes, I am tired, I need some sleep.« and with more effort one could build a robot that behaves as if it was tired.

On the other hand I have a lot of sympathy for something I heard the first time from Daniel Dennett, that something like pain is just the sum of its effects. It occupies your mind and prevents you from thinking clearly, it makes you not move or touch the body part that hurts, it dulls other sense, and so on. If you removed all those effects, what would be left of pain? With that understanding you could probably probe if something is experiencing pain from the outside by looking for those effects.