Iceberg lake is in the North Fork Canyon and Trail camp is in the canyon to the south. The Pinnacle ridge seperates the two. It is possible to cross the pinnacle ridge at the Pinnacle pass. That is class three cross country. Certainly not an easy task with a backpack. It would involve some climbing and crossing moraine fields.
The Pinnacle pass is the low point about 1/2 way between the Whitney crest and Thor peak...just a little south and west of Barney (Girl Scout Lake). Just next (west) to the pinnacle pass you will see a spike sticking up (called Pinnacle point). This will be obvious as you hike from UPSL to Iceberg lake. Say 1/3 to 1/2 the way between the two lakes off to the south.
http://members12.clubphoto.com/robert634908/2353168/guest.phtml In Bob R's photo album look at picture #71. This was taken from the Whitney Summit. Follow the ridge from Thor peak toward the low point. That is pinnacle pass. On the North side you can see a large snow field approaching the pass. What is out of the picture is the rest of Pinnacle ridge extending west to the Whitney crest. You can see more of the Pinnacle ridge and Wotan's throne in picture #72
If you prefer, you can carry your gear over the summit of Whitney from Iceberg lake and then go down the trail to Trail Camp. That involves some real effort also.
Staying at the base of the Whitney crest and just walking from one to the other is not practical. The Pinnacle pass is very steep on the north side at that point....class 4 or class 5 for sure.