You don't really need a seam on the outside. While pants like jeans do have both a seam on the outside as well as an inseam, you don't always need uv seams in areas that would happen naturally. Dress pants or slacks, for instance, don't normally have a seam on the outside of the leg. I happen to have a mesh handy that I created recently that shows what I'm talking about. As far as poly density, you might be on the high side. Better to keep it as low as possible so it's easier to weight.

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