a planar projection from the y axis will look good on the top but will cause warping on the sides. the reason why i even suggested automatic projection is because then you'll have projections of different sides of the model that you can then piece together.

as far as sand goes, grain isnt really appearent unless you get fairly close to it, what tends to be appearent though are ridges made by the wind, tracks, rocks sticking through it etc. so watch out with the bump or it'll look like a miniature set. photo refs can be misleading because alot of photos tend to have some grain anyway.

far shot


close shot