You definately want to get a two stage air filter, one grain of sand can kill your engine. You also may consider using silicone to seal the bottoms of the diff. housings, goto
http://www.hpiracing.com/index2.htm and look at the FAQ forum for more tips and info. Other than that, you shouldn't have any problems running in the sand. You might not want to get the truck near the wet sand too much because of the salt in the water is very corrosive to some metal parts.