Ready? Everything in this post is totally "TMI," or, Too much Information. All from a male perspective.
I went nude pretty much every day, and the worst part of the whole bit was definitely in-between the cracks, so to speak. Sitting on my bike seat, going for a ride, locking it up, wandering around, going back, riding around, doing that whole bit over and over and over again definitely gave me playa-ass. I kinda... well, i kinda wiped my ass with moisturizing lotion to fix it, but it kinda stayed rough. I tried some vinegar, but the smell coming from that... was pretty nifty, I must say. My lotion kept it all okayish, but it was still a bit dry-swampy down there! It made my late-week #2 sessions... interesting.
I'm also a european-style man in the front, if you catch my somewhat-generalized drift. I made sure to keep the armor up, and i still made sure to moisturize. One mistake I made that I will rectify for this upcoming year - if you're hairy, shave it. I kept ending up with splotches of dust that were kind of a pain to get out. Maybe someone else can chime in here - I feel like shaving it about a week out to get past the itchy phase and to end up with peach fuzz(?) might be a good option.
The dust seems to effect different people in different ways - some people can go barefoot and naked all week and not have much of an issue, some people get rashes and cracks all over. Re-iterating what others said - the medics are absurdly nice and helpful, almost to a point of it being a bit wacky. If you need help or have questions, go to them!
Other than that, sunscreen absolutely everywhere. The sun is wild out there - I made sure to apply twice daily. I didn't really get burned, I consider that my Mexican bonus for being darker skinned plus proactive about sunscreen, and beyond my dry-cracked-asscrack, I was pretty much fine. Always better safe than sorry, though!