Perhaps the salting is making your eggplant mushy? I don't salt my eggplant so I can't say that's it for sure.
Breadcrumbs or panko are not traditionally used in moussaka but that doesn't mean you can't try it. My guess is that you would get a goopy mess this way as the dish releases a lot of moisture but who knows, it might work.
I don't fry any of the ingredients in my moussaka, instead I brush the eggplant slices with olive oil, OLIVE OIL for greek food!! Then I lay them on cookie sheets and roast till desired tenderness - which for me IS mushy but you can do it less. At this point I also use zucchini in addition to the eggplant. It adds a nice flavor and a wonderful texture which sounds like what you're looking for.
The most important thing in the moussaka is the potatoes. I know many recipes call for the potatoes to be fried before they're layered into the dish but I put mine in completely raw. Just lightly oil your casserole dish with olive oil and then lay down the raw potato slices. Sprinkle with salt before layering in the other ingredients. The potatoes act like a sponge to absorb all the oil and moisture of the other ingredients. As you can imagine the potatoes turn out to be the tastiest part of the dish.
I never tire of eating or discussing moussaka.