First, skip the "dog park", as they are for TARDS'. Period.
You yourself wrote...
I can only think of 2-3 dog handlers in the park who do training with their dogs. It's appalling.
...so you are aware of the problem.
So why go?
"Dog parks" are not only a haven for retarded clueless owners and their untrained mongrels, but they're also a haven for untreated / undiagnosed canine maladies that get passed along via "play", ingesting contaminated feces, fights, or whatever. I wouldn't EVER bring my dogs to those places as they're basically canine cesspools.
Second, if you want your dog not to fight other dogs, it's going to have to have confidence in you as a leader and protector. That means you have to step in and resolve aggressive situations BEFORE the other dog can get to your dog, which isn't too much of a challenge with most pet dogs. If you don't have the physical bearing or composition to impose yourself between two dogs, then ALWAYS walk with a big ass "walking stick" and use it to steer away / beat the shit out of any aggressive pet dog that comes your way. When your dog sees, and realizes, that YOU are the one that will "take care of business", they will defer to YOU when other dogs show some aggression.
Lastly, a fairly safe option to break up a dog fight is simply to grab the aggressive dog by the rear legs, spread them apart, and while pulling the dog off the "victim" dog, swing the little guy in a circle so he can't simply turn around and bite you. TWO people are preferred for this technique, one for each dog, but you can usually manage it alone in a pinch. If you find a dog not wanting to release a bite grip, a knuckle punch to the asshole is usually enough to make the dog refocus and release the bite. Make sure you have a plan for what you're going to do with the dogs when you DO pull them apart, be it a boot to their ass, or whatever.
Best of luck to you and your dog, regardless.
