Chief Law Enforcement Ranger Barry Nelson is incorrect on a couple of points. First of all, the County of San Bernardino took away the authority of the BLM to enforce State laws on Federal lands. This was recently confirmed with Mr. Bob Smith at Postmus' office. The BLM do not have the authority right now to arrest you for violating state laws.
Secondly, I think we will find that the law has interpreted that just being nude is not considered "lewd". You have to do something more than just be nude. You have to be conducting yourself in a sexual manner.
At this point I think it would be wise to get the advice and assistance from some of the larger nudist organizations. They have attorneys and have an interest. I will contact them and post their responses.