Practicing being alone is very useful. However, I would suggest practicing it after a long walk or when the dog is worn out, so he doesn't have the energy to put into being anxious.
Also, leaving the dog with a (single) chew toy is probably better than leaving the dog with food.
You may wish to train being alone with a crate.
- Wear dog out with physical activity
- Put dog in crate
- Close crate, reward with food
- Turn around and walk a step or two
- Immediately turn back around and open crate
- Let the dog out
- Repeat, but each time walking further away when your back is turned. Eventually you should walk out of the room, then immediately come back and open the crate. Then once the dog is okay with you walking out of sight, work on duration; stay out of sight for a bit longer.
- After this, you can work on leaving the house, and then building duration when out of the house.
Of course this method, means he needs to like his crate.
Also, I wouldn't turn the tv on, unless he's socialized to it and it's on a lot when you're with him. Otherwise, it will predict you leaving, and he might start to freak out when you turn it on. i.e. whenever you turn it on, you leave, so he becomes anxious.