Just for girls
Skirts are lovely to hike in. Cool in summer, but still providing protection from sunburn. With judicious care, it is possible to pee right on the trail. At first pass this sounds not at all Leave No Trace, but the trail is the most impacted ground around and urine will not have as much effect on impacted ground.
I usually hike in a Macabi (skirt) but any nylon skirt will do. The Macabi has special features like a small zippered pocket for keys and small items, a clip which allows one to turn the skirt into baggy pants (useful for rock scrambling, high winds, or rock scrambling in a high wind), and snaps which turn the skirt into a mini. I have also sewn my own skirts using a Stretch and Sew pattern. In cold weather I wear wool long-johns (long janes?) under the skirt.
When pants are advisable, I add a long invisible zipper in the crotch so I can upzip and go without squating. I make my own, either by sewing the pants from scratch or by splitting the seam of a normal pair of hiking pants and installing the zipper. An elastic waist and stretch fabric work best.
There have been at least two companies which attempted to sell these pants for women, and both of them have failed. Some mountaineering sites sell a heavy-duty version, but they are as expensive as mountaineering gear usually is, which is to say, very.
For crowded trails or when one is wearing pants, the GoGirl is a female urination device, of foldable medical grade slilcone. Pink, of course. I usualy hike with one in my pocket.
To expedite these matters, I carry a pee rag. Leave No Trace advises us to carry out our used toilet paper, and many National Parks also require this (no, it won't disappear if hidden under a rock -- or even on top of one). A pee rag, which can be an old bandana, or a small piece of a hiking towel, hung on the back of the backpack will sterilize itself in the sun between uses.
For hiking undies I like what my mother used to call "old lady underwear" Or granny panties. That is to say, full nylon briefs. These act as a liner sock for the hips, protecting the skin from rubbing via the waist belt.
Always carry a couple extra feminine hygiene items, even if it is not time for the monthlies. Exercise sometimes throws the system out of balance. And yes, they do have to be carried out. They do NOT biodegrade.
Gone are the days when we were advised to avoid strenuous exercise during "that time of the month". Anyone remember the little movie that showed a girl horseback riding, and listed that as one of the no-nos? Some women find they become more easily dehydrated, but that is fixable by drinking more.
Opinions are mixed as to hiking in bear country during one's period. For myself, four months hiking solo in Glacier National Park at all times of the month did not result in any bear contacts, or even bear sightings. Though it is always advisable to secrete any items with strong odors in odor-proof containers when in grizzly territory. Perfumes and scented make-up have the same caveats.
Speaking of make-up, don't. Sweat will make the colors run. It is hard enough to stay clean without having to deal with cosmetics, and who wants to slather on a foundation base over dirty skin? Men on the trail do not expect to see painted women: it just doesn't compute.
I do enjoy washing my hair when possible, but remember: soap does not go into the water supply, even biodegradable soap. Soap is poured into the soil 200 feet from the water. I have tried non-water shampoo, but I haven't found one which seemed to work for me. A hat always works for a cover-up.
Wet wipes can give one the impression of freshness, but again, carry them out. They contain fibers, and these do not biodegrade anytime soon.
Showing off the Macabi skirt