Not being a modder myself, I don't know how difficult this would be. Having Thieves Guild pants added to the Hide Armor without altering it otherwise, just to add additional protection to the legs would be an excellent change, and it's been done in a way already on the Ranger Armor in the Immersive Armor compilation by Hothtrooper 44: http://skyrim.nexusmods.com/mods/19733 This one appears to be Studded Armor with a few changes and the addition of leggings, rather than Hide Armor, however. Despite it being a low level armor, it does show up quite often on bandits, hunters, and misc. NPCs in the world. To be specific, my suggestion is to add leggings, perhaps Thieves Guild as shown on the Ranger Armor since they appear to match the color and texture of Hide Armor well enough. The addition of some chainmail pieces, bone decorations, potions on a belt, or other frills and decorations might make for a fine standalone armor set too, if anyone wanted to make a hunter or skirmisher oriented set. I personally think a set made from the base hide armor could look quite good for a rugged hunter oriented character that didn't mind the cold. This is something I would like to see, but as I may or may not be able to visit the forums often to check this post, I will offer my thanks in advance to anyone who likes the idea.
