I think you’re assessment is correct. There’s nothing on that ridge in the way of water sources. If coming up from the Vivian Creek side, the last reliable water source is High Creek. If you’re coming up from the Momyer Creek/Falls Creek side, then Plummer Crossing (very reliable) is the last good water source.
If you had a three day weekend and could get a permit, you could do first night at Saxton and second at High Creek (or vice versa). You’d have reliable water both nights.
Map link: http://caltopo.com/m/0P77