It seems that much of what people here suggest you have a reason why it won't work for you or your dog. Maybe I'm reading it wrong...but sure seems that way to me.
I think that I have run dry with ideas to help you. You really need TO FIND A WAY to impliment some of the suggestions that posters have made here.
All I can say at this point is good luck with your dog. I hope that things improve for you both.
Well let me say this then if it will simplify things... Am I a trainer? NO. Am I a certified dog/animal behaviorist? NO. Have I ever owned a dog/been around one that has behaved like this dog before? NO. Does my/Have my other dog(s) questioned who was in charge..a reverberating NO. I give them the evil eye and they run for cover--they know when they have done something wrong, when/what they are not allowed to do, they know their place. I haven't raised him any differently than my other dogs, and yet he is always testing the boundries. Which would tell a person.."hey, you are doing something wrong." HENCE the reason why I am here. Do I know exactly what I am doing wrong, or how to fix it? Obviously not, or this dog would be like any other that I have ever raised.
There is only so much that can be said, you are not here, you can not see what I do/what is being done. So I'll give you that.
Maybe you would treat this dog differently, because you have had a dog with 'leadership issues' I HAVE NOT. I don't see how the heck a doggy door would create an issue. Or letting him have supervised time with a toy or bone = leadership issues. He gives the toys up when I feel playtime is over. He doesn't claim furniture or objects as his, doesn't challenge me for objects/food--something that would have lit the obvious red light "leadership issue".
Did I let him get away with attacking power tools..the hell I did. He dose bark at the saw--that is a new sound to him, one that we just discovered and have been getting him use to.
The issue of the treadmill--why this seems to be a big deal, I don't know. Would he get used to it if I got one, yes. Would I use it, I don't know. I have heard things good/bad about their use, and without doing more research I don't know if it is a piece of equipment I feel comfortable using. As a pet owner I feel it is my responsibility to look into these things before I willy-nilly leap head first into it...Pardon me for exsercising caution and not taking every word/ piece of advise I hear as gold on a plate. There is ALOT of bad information on the subject of animal training as it pertains to behavior.
As for making up excuses... sorry if I don't feel like sacrificing the only 4-5 hours of sleep I am lucky to get over a damn pain in the ass dog. I HAVE conscidered suggestions, do I feel they will work for me...I don't know haven't tried them yet.
When I seem to ignore advise, I am either already doing it, or have been told not to for what ever reason by the trainer/behaviorist I consulted. Or to put it this way rather, would you be ticked if you told someone to do something, they didn't do it, and then came back and said "what you told me was wrong, he's not doing what he's supposed to"--well did you do what I told you? "No"-- and there you go...
And unfortunately there isn't an easy fix-it-all button attatched to his fat head--training takes time. Results take time, they aren't going to magically spring up. My dog is not ever going to be a perfect model citizen--I have been told that by a certified and studied animal behavorist, he is what he is--the best I can do is manage his behavior to limit the severity of his reactions--any new ideas for enriching our lives and exploring new options for keeping him busy are appreciated despite what you must think.
Further more, there is a TON of information on how to desensitize, peoples opinions on the best methods/approaches to obedience training, Behavior modification, And what not.. I am only just beginning to scratch the surface and sort this crap out for myself so i can begin to better help him. I only know what I know, and what I don't know I approach with caution.
I do know that I don't want to get bit by my dog. And shouldn't have to. I am learning to read his body language, and can gauge pretty accurately the way he will react to certain situations...do I stop trying NO, I try to find a different way of introducing him to things that doesn't increase his stress level to the point that he is too much for me to handle. Or THAT he stresses me out and I want to strangle his ass. Both are counter productive...
I feel that a successful training session starts and ends on good notes. And as for being a good pack leader--how many people Reeeeaallly know what the heck that means, or how to attain that position? I'm sure every one does which is why so many dogs are surrendered... and Has anyone explained this...nope. Or offered a 'better' way of leading my dog since he is obviously such a spoiled brat who gets to do everything he wants? We'll see..
And if he has to live on the side of my house like the hunch back of arizona, then so be it..I am not going to set him loose on craigslist hoping there is someone who has more knowledge and is willing to work with him. Odds are that won't happen-- Even if it did, the strange new person would have to sedate him to get him to the car.. he will not, NOT let anyone he doesn't already know touch him...which is fine by me, he's my dog.