Peemate - A dutch equivalent of the Sheewee.
I have been surprised how many women have been embarrassed by the idea, but I love them!! There's no need to bare your bum, and definitely no need to risk squatting in any nettles or nasties!
Carry a few zip lock bags with you, so you can stow the used one away if you don't have anywhere to dispose of it.
I found that the peemates fit perfectly in the back zip pocket of my jacket (for hydration packs), so are easily accessible.
Underwear riding up your sensitive bits is really uncomfortable, never mind things like thongs that have no choice but to ride up!
Thank goodness for hotpants!!
Fashion has come to our rescue and made girl boxers. Phew! They're great - excellently comfy, lets you move about and do whatever you like without being uncomfortable. And some are very cute

Also less of an issue airing your laundry after washday, because they attract less attention than frilly lacy things. LOL
I'm not a fan of synthetic hormones, so the pill isn't an option for me. But what I have found really great for balancing mad travel hormones and getting your cycle sorted so you can at least prepare for when you will need to, is a herb, Agnus Castus. Available in a tiny bottle of liquid, or in tablet form. A great help if you know that travelling messes you up a bit.
I second the Wet Ones/Wet Wipes - they're gold!
Also really useful is the no-water-necessary alcohol based hand cleaner. Cleans even greasy dirty bits and can also double as a facial cleanser/toner.
And ziplock bags are handy for loads of things and can be reused if the previous contents weren't icky.
I'm definitely packing vodka for the next trip
(oops! I forgot to add - Boots and Superdrug in the UK make great plastic travel bottles with screwtop lids that are very secure. I decanted all my shampoo, conditioner, bodywash and clothes washing liquid into them and was set for over a month. Another option is to just save old plastic screwtop bottles from household/toiletry stuff for a while before your trip, then you can pick and choose the best sizes to re-use)