If I wanted a specifically snow capped mountain as a hand-drawn element, I would do something like the attached. Basically, I'd draw a line with a lighter touch as a defined "here's where the snow begins". Since I include more surface detail than your maps, I would additionally insure that hatchwork beneath the snowline is heavier and closer together, while any hatchwork above is less, simulating lighter shadows on a lighter surface (snow covered).

GP

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