For a 2-night trip, consider camping at LBSL and leaving for the summit earlier in the morning. LBSL is only 30-45 min away from UBSL on the way up (unless you plan to hit the route in the middle of high snow winter, which a different story), but it is at lower altitude and offers infinitely better camping - more protected and, arguably, more beautiful. Not to mention that with this strategy you will have less travel with a heavier overnight pack. I would leave around 5AM to have enough day light while navigating the slabs and to have enough time to enjoy the camp after returning from the summit. Most folks do the MR car-to-car in the summer and fall.
