In July, 2001, my son and I did just that itinerary...Portal to Trail Camp, summit with day packs, Trail Camp back to Portal in 3 days. (Had a 4-day permit in case of weather problems, but summitted on the second day, so headed back down the third day.)
We left the tent set up with our sleeping bags, etc., in the tent. Backpacks were stacked together with a large trash bag over them for rain protection (needed it). Food and "smellables" (i.e. toothpaste, etc.) were in a bear can away from our campsite.
Nothing was bothered...when you're already 6 miles and 4,000' up the trail, not many people are going to lug stolen goods that far back down! Trip report under the "highpointing" section of my <a href="http://www.mtritter.org">WWW site</a>.