High Sierra Topix

I'm planning a trip to Mt. Langley for mid-July and was wondering if anyone here had any tips for camping at the Cottonwood Lakes Trailhead. I plan on driving up from the LA area on a Friday and sleeping at the trailhead. The campsite info I've found so far indicates only ~18 sites, first come first serve. If those are full would I get into trouble if I just threw out a sleeping pad on the ground at the trailhead? Would actually pitching a tent get you in hot water?

Thanks,
Erik

Shouldn't be a problem- if its all full you can walk the 100ft into the Golden Trout Wilderness and sleep anywhere you like!