Diaper is gross, but peeing in a bottle while sleeping in the car can be nice. Just roll over, pee, roll back over and fall asleep again. Much less intrusive than getting up and walking to the bathroom, dealing with bright lights, etc.
There’s a device called a she-wee and many female vanlifers report success with Folgers tins or large fountain drink cups, which then get poured into a bottle.
While my personal urinating experience so far in life has involved a male urethra, I met on trail women who've been using Shewee for peeing in the outdoors. I imagine that if it works the way it's supposed to work, maybe it could work with a bottle.
