With +R you should always provide an alternative - don't go there, but what is instead? Sitting or lying down? Come on, it is hardly stimulating. Keep your gate open, recall your dog every time he sees something interesting through, take him to the gate on loose leash yourself straight away walking slowly, step out yourself first and go for a short walk around. It works as "If you want that - you should do this". At the beginning of training you should achieve your dog calling you to come with him to the gate by jumping and hitting you slightly. You don't have to go out if you don't feel like it, just poke your head out and let your dog do the same. If your dog barks - it's just fine, train him to bark on command while looking through the gate. Train him "Quiet " after, "voice"-"quiet" in repetition. That is rewarding. Your dog learns to stay inside only because you don't go there. "Stay" works only because you call him out after 1-2-3-30 minutes and reward with a walk.
If your pup shows such a success now - most likely he will remain like this all his life. My Lucy is a "walking goodness", it never took longer than one day to learn a new command, she is three years now and learns like a five months old puppy. Her last achievement - to search a buildind site for the object with one of smells she knows while we are waiting at the entrance. And, if you might guessed, the principles of training are similar - "you can get what you want if you do this". The NILIF gets to the core of the dog's brain, it was the greatest treasure I ever found.But you know ...We are humans, we cannot be satisfied, we always want something we don't have. Lucy is not a sports dog.