Over the years, we've seen plenty of illustrated Barsoom, from the aforementioned covers by Frazetta, Whelan and others, to the interior illustrations, to a Marvel comic. They all depicted a fairly uniform look to the material, and none of them needed to venture into nudity to be 'accurate' to the material - and I doubt it bothered anyone; even knowing how Burroughs described his characters, my personal vision of John Carter and Dejah Thoris is that of the art we bought with our books, and as long as the movie has a similar sensibility, in both character and set design, I'll be happy as a clam! 
