My husband spent three illegal hours in a shop and then came home with stuff to make the couch squirrel-proof, Red has been running around for an hour now without sneaking into the couch! <3 He's now stealing the apple off of the bird's perches and hiding in his newly made hammock. I made one about the size of the ceiling of his cage to avoid him from backflipping and it's working! He still tries to but now he has to make a lot of different movements to succeed, instead of just repeating the same back-straining movement over and over.
He also really sees his cage as home as this is where he returns when he spooks or when we clap our hands to make him leave spots he can't go. That's super helpful too, he will return to his home at all times instead of sneaking away to hide!
Success!!!