I can sympathize intensely with this situation!
With my dog Glitch, he has been this way since he was a little puppy. When he was younger he would just want to play with and be with dogs. They would get tired of the little puppy and growl, and give him very clear signs to back off. But he never would. He ended up getting bit seriously about 3 times, countless fights. He would never be the attacker, or the first to snap, he would just be pushy into other dogs until he forced them to attack him.
He is almost 14 months old now. And progress has been very slow, I am sure this is something I will have to work on the rest of his life. Here is what we have been doing (and suggestions and comments are GREATLY welcome, this is not an easy problem, and I am very open to things I could be doing better):
First I should start out with the fact that glitch has a very strong foundation of training. He can recall, plotz, sit, with perfect accuracy in almost any situation. He loves to train, and I love to work with him, so it has been great to push him into harder and harder situations. At this point there is no distraction I can create in a training situation to phase him. I can call him away from his food, I can make him run past his food, I can have him run commands while someone else is playing with his toys, or even playing with another dog. And yes, he even responds while with other dogs (although you can tell this is easily the hardest situation for him).
I at first wanted to do as many suggested, just don't let him approach unless he is calm. But that really does not work so well for glitch. I can put him in a sit, I can put him in a plotz. He reliably remains in position/command even when other dogs are close by. But it drives him crazy, he just whines, and cries, clearly very anxious to be released. It obviously does not help him improve the behavior if he can't engage and deal with other dogs. And similarly if I do release him, his excitement level is even higher. One day I hope I can have him to where he can't approach other dogs until he is calm, but he just gets so fired up, and even though he obeys, he just struggles to focus. So I been working on a strategy so that I can get him to be around other dogs, without having him be under command first.
The electronic collar has been a key layer in his training for a long time now. He is very familiar with it, and is very collar conditioned (meaning he recognizes how to stop the correction). We use it both for enforcement in difficult situations, as well as making him tighter (quicker responses).
I too, just like you, was very worried about using the collar correction in social situations. (not sure if your using an electronic collar, but the big advantage it provides is timing, timing is everything when your trying to correct a situation, you must correct at the exact moment in order for him to make a correlation to that specific action/command). He was always friendly, tail wagging, sniffing, never showing any signs of aggression. But at the same time he was being very confident, pushy, and assertive. So basically I had one primary fear when correcting him, I did not want him to associate it with the dog, and thus did not want to change his pushy behavior into aggressive behavior.
So here is the steps I been doing to try and help the situation:
1) Neutered him, don't know if it will help, and I really wanted to avoid it. But at this point I feel it is a very difficult situation, and probably one I will have to deal with his whole life. So I decided to do it, in a little chance that it will at least help my odds that it wont become aggression.
2) Been including the "leave it" command in our formal training sessions. It is just like any other command, with the same rewards and corrections. He already knew the command, but we had only worked with it in informal ways (while in the house, etc). Now it is part of our formal routine.
3) We already had the command "back" in our formal sessions. Meaning to back straight up about 1 or 2 feet. We used it when he is being too push (and similarly don't let him walk between the couch and coffee table due to tail dangers). In our formal sessions we may make him back away from us, even at a distance of 100 or 200 yards.
4) Soon we plan to start training next to dog parks (just waiting on him to heal from the nut chop, before we start training again), hopefully on the other side of the fence. So he can get more used to following commands and responding when dogs are near by.
I still try to avoid corrections while in social situations. But at least with this strong foundation, I am confident that if I do need to correct him, he understands very clearly why and where that correction is coming from. Corrections are not a new thing, and hopefully I have brought all these things into his formal sessions he will understand he is not being corrects form the other dog, but rather because he is expected to follow the command.
Basically it goes like this, if he starts getting too pushy, or too assertive, I use the the "LEAVE IT" or "BACK" command (depending on how much I want him to back off). A firm bark at him, making sure he hears me, and understands. 90% of the time, that is all I have to do. That way when he is getting too pushy, or too assertive, i just tell him to leave it, and back off from the dog. If I ever do have to correct him, hopefully he will understand it is not from the other dog, but rather because he did not obey the command I provided first (leave it, or back). To further make this point I make sure I am corresponding the correction with at the same time saying "NO!, *repeat command*" (which is good practice ether way, just really trying to be extra much on my game during social situations).
Success? I have had varying degrees, he certainly has not become aggressive yet. He has certainly got better and less pushy around other dogs. He can now be with other dogs and will leave them alone, and not be too pushy. But in order for that to work I have to be there, watching closely, and frequently need to tell him to calm down. He does it, he is getting in patterns of good behavior and is improving, but I can't trust him to be with other dogs without me, or someone who understands him well enough to keep him in the proper behavior. It just requires constant work for my high drive dog.
But otherwise, I also recognize he is 14 months, I hope that two years down the road things will be better. But I have a nasty feeling this will be a slow process that will probably never be finished.
Sorry for the long post, hopefully that can be helpful. Not trying to hijack the thread, but I am very open and welcome to comments or suggestions, this is not an easy problem and am open to anything I have not considered.