Last day, I would do LSL-USL-up the use trail to Langley-drop pack/summit Langley-get pack-NAP-out. That is a very long day though. But I prefer that route from the Soldier Lakes to Langley rather than all the extra miles of going around and then up and then across the plateau...the use trail above USL is scenic and more direct.
Btw, I also like the traverse from USL to the Miter and back better than the route options from LSL. But it all depends on how good you feel about your route finding ability.
