Grid based damage markers

So I’m very new to Vassal and I’m trying to get a Vassal mod for a homebrew space combat game I’ve been working on. The biggest problem is finding an elegant way to get damage markers to appear on the ship models. The game uses models that are 5x5, 5x10, and 5x15 grids for various sized ships. And when those ships get damaged you put a / or X on that ship grid. So I’m trying to find a way to get these models so that if you click on the grid, it toggles between blank, /, and X. And I need these markers to follow the model around and rotate with it. The closest thing I’ve seen so far to this was in a mod for Warmachines tracking Warjack damage, but if I was to do this exactly as they did, I’d be making 300 different jpegs with / and X’s in different locations. I’d prefer to avoid that if possible. So anyone have suggestions on how this might be done?

Use a layer with three levels? They would be: invisible, / on invisible and X on invisible. Place the layer trait before the rotate trait.
You might be able to recycle the same for the various ships (just offset it appropriately) or you might have to make one for each type/size of ship.