I recently saw a vid on youtube where someone troll picked nami as jungle...but then did seemingly well, so i tried it out since nami is free this week and went 6-12-20, and was just looking at ways i could improve either my build or her clear speed as that was really her main weakpoint.
I don't even know how this would work... She hardly does any damage and doesn't scale nearly as effectively as other champions with flat AP items. You need to use armor runes (and maybe even an armor item) to keep her from being eaten alive in the jungle, leading (I imagine) to a very slow clear speed. Her movement speed is low. Unless you build armor/magic resist she will be instantly blown up in team fights. All of her weaknesses as a support are amplified in the jungle. You are effectively asking your team to carry you into the late game when you might be relevant.
Go with atk speed runes that one would use for several other junglers, and make use of her W. Trailblazer would be an obvious item, perhaps Nashor's Tooth and Wit's End, other items that make use of on hit effects and offer ap/atk spd
