Man, if you take a beast like a Burb onto sand dunes you will be asking for trouble. Because of it's wheelbase length and weight I guaranttee you will sink it up to the axles.
Wide tires will be the best thing for Sand. I build rockcrawlers-- love tackling obstacles normal 4 wheelers don't even think about.
Heres a pic of my 93 Burb 2500 that I pull my trailer with. It has 108,000 miles on it.
Bill