Even though you're from Tuscon, remember that a little extra care should be taken at White Sands if you're there on a sunny day. The sand reflects an amazing amount of light back up from below, and you can easily get overheated even if you shade your face from above with a hat brim. (Take it from someone who spent a lot of weekends there during his college years.) If you'll be there during the day, take more water than you think you need.
You might want to grab three frisbee-type toys for use under your tripod feet. Depending on the weather and wind conditions in the days before you get there, the top couple of inches of the sand can be soft in some places. The frisbees will allow you to set up your tripod without having it sink too far into the sand.
As always when you're around sand, beware of the wind if there is any. The gypsum sand at White Sands has an amazing way of getting into just about everything. Thankfully it's softer than most sand, but you should still plan on spending the evening cleaning out your gear when you're done.
If you can make the arrangements ahead of time, it's worth paying the fee to have a park ranger meet you there an hour before sunrise so you can get in and get set up before the sun comes up. Very early morning at White Sands is a spectacular time, with the long shadows adding texture to everything.
Also, depending on what type of photographs you're looking for, you might want to stay closer to the edge of the park rather than travel into the depths of it. The edge of the park has a lot of plant (and animal) life; go in a few miles and all you'll have are endless dunes. The dunes shift too much for plants to get much of a foothold, so the dunes are very bare deep in the park. Depending on what you're looking for, you can find two very different landscapes in the park.
Best of luck with your shoot. I wish I'd been a large format photographer back in the '70s when I was living in Las Cruces.
Be well.
Dave
