I maternally incubate all of my ball clutches. If you're only going to be gone for the weekend, I wouldn't worry and unless you intend to allow her to brood the clutch, I wouldn't bother with lining the tub with moss or another humidity-friendly substrate or medium unless you prefer the look. However, if there is room for a humid hide/nest box big enough for her to coil comfortably in, it might provide a more comfortable lay site for your female since you say the humidity in her tub is very low.