The Racetrack is one of the most amazing places in Death Valley. Both dawn and dusk can be good, and I still want to return to get star trails. It gets very cold quickly at nightfall this time of year, no doubt even colder at dawn. It's high enough to easily get below freezing (that's apparently how the rocks move, embedded in thick floating ice). The drive out can be completed at a fast pace in about an hour on heavy washboard gravel from Ubehebe Crater (where the paved road ends), about 90 minutes from Scotty's Castle, but it may be wise to take up to 2 hours for that last 29 miles. The paved road from Scotty's Castle to Stovepipe Wells is another hour.
You can't camp near The Racetrack, but you may be able to find a turnout up near Teakettle Junction. With the sun setting behind nearby mountains by 4pm or so, arrive by 2 so you can walk a mile or so to the moving rocks (far Southwest corner of the playa) and find the rocks and shooting angles you'll want to catch as the light gets good.
If you have a GPS unit and may be out until sunset, mark your car position so you can find your way back after dark. There may be some water to get around near the parking lot as well. The playa is closed if it's wet and muddy; the visitor center (or a site like DesertUSA) may have details on recent conditions to spare you a long, fruitless drive.
I've punctured a tire on 50% of my visits to The Racetrack (and I've had off-road SUV tires disintegrate on other washboard roads), and the Park Service recommends 4WD, high clearance, two spares and plenty of survival supplies. I've lost 5 or 6 tires to gravel roads over the past 3 years. I've simply been lucky not to get two at once. I carry two cans of Fix-a-Flat in case a puncture is small enough, but it the failure is rarely that small or simple on those roads, and sometimes those cans have gone bad and don't work (carry 2 different brands), perhaps due to the occasional heat of desert travel conditions (particularly in your locked car at a trailhead, even when the outside conditions aren't that hot).
The road to the Racetrack was in relatively good shape when I visited at the beginning of December... still crappy with very deep washboad that rattles your vehicle at any speed, but the additional baseball-sized rocks that pummelled my SUV last year had been graded to the side. The road from Ubehebe Crater to Eureka Dunes was also in better shape than on past trips, though still an hour or more of punishing rattling, and still rated by the Park Service as poorly as the road out to the Racetrack. Road conditions can change dramatically with one storm, so who knows what they're like now.
I don't yet have dates nailed down to offer a Death Valley workshop this year, but if you're interested in going, contact me and we can probably work something out. At a minimum, I'd like to visit again in March when wildflowers will add color to the park's incredible landscapes. Most photography tours to Death Valley don't visit the Eureka Dunes or The Racetrack, arguably the two best sites in the park. I can't imagine visiting the park without them!