Whatever tent you decide to go with, think about treating it with premethrin before you leave. It'll kill, not just repel, many of the insects you'll be encountering for up to 2 weeks. It works.
If you're looking for truly ultralight then check out:
http://tarptent.com
Henry's tents are highly regarded in the ultralight backpacking world. I've used them and they're impressive, but wind is sometimes an issue. Choose the attached floor option. The Squall 2 is phenomenal.
Another good alternative is the REI Quarter Dome, which I think is the best bang for the buck and just got Backpacking Magazine's Editor's Choice Award for 2008. I haven't used the improved versions but I've used the old style in really bad mountain conditions without problems. They're now made in 1, 2 & 3 man versions. Mostly mesh, so they breathe well and they have a light colored rain fly, making them cooler in the heat and brighter inside. If that's too much mesh due to blowing sand they make a version with less mesh also.
http://www.rei.com/product/761893
I use a Black Diamond Beta Light tarp (with the mesh body and attached floor for buggy conditions). Mine has withstood taifuns in Japan and equally bad whether on mountains around the world. It uses a silicone impregnated nylon for the fly and packs down super tiny. It's also very expensive and it uses trekking poles for the tent poles, so it's probably not what you're looking for.
Putting stakes in the sand can be problematic. You can tie your guylines to the middle of your stakes and bury them side ways (instead of driving them into the ground, which works in sand that's not too loose. If it's really loose sand you can make dead man anchor's from plastic grocery bags. Attach them to your guylines, fill them with sand (or snow in the winter) and bury them. Throw them away when you're done and it's one less thing for you to carry around with you when you're done with the camping portion of your trip.
As far as footprints for your tent, go buy some 2-3 mil plastic from your local Wallyworld to make a throw away footprint so you're not hauling all the extra weight around with you after you're done camping. Not great for the environment, but it's cheap, light and effective and would be ideal for your trip.
Hope this helps