Hi,
don't abandon the idea of a dog walker. A dog walker will get him used to another person and also expose him to different situations /environments that you may not. The point about not wearing them out is correct. I take my GSD on 20km horserides and does not wear her out. She is the only dog that after a canter on the horse is right there by my side, no waiting for her to catch up. My dog has dominant issues as well (i live in the city) but when she is exercised they are not so evident. So point being if you can afford a dog walker, give yourself a break, expose the dog to a different "handler". If you ever go on holidays you want the dog to be able to be cared by another person.