Right after defeating Amaru upon that City of Serpents you can find Moraekah upon that Kuwaq Yaku location near its Hunting Grounds' Camp Fire. Although after that one time I simply don't know where more to find her.

The best trick is to go hunting before heading towards her and bring a lot of valuable items / skins to sell before trying to obtain those said items from her.
And don't forget the exploit to pass through the Kuwaq Yaku's entrance into the Peruvian Jungle through that cave because it always has Fat and Cloth (alongside a few Arrows) to be picked with no effort at all).

Informational side note: Although I've never needed that upon my 1st playthrough because always had available space to get items by selling a few of every type when those reached their maximum amount. In fact, upon my 1st playthrough I've even reached the game's maximum cash of 64k, so...