I was up at TM Friday night and Saturday. No smoke at all! I checked the Yosemite web cams Friday, and it looked like there was some smoke in Yos Valley. Prevailing winds tend to come from the NW, so smoke is likely blowing mostly out toward Mammoth.
I took my daughter up Friday night (late) to TM, and just laid out sleeping bags by an unused camp site. They put up the Full campground sign when all sites are reserved, and have no method of giving away the unused no-show sites. We picked an empty site in the horse camp area (Elizabeth Lake trailhead), but were packed up and out of it by 8 AM. There were other unused sites across the road from the Elizabeth Lk trailhead parking.
By camping permits, do you mean overnight trail permits? You should call the park info and ask about such things, but I believe the Wilderness Permit office about a mile east of TM will have no-show permits.
