I quite often have to change in my car - sometimes this way, sometime that way and sometimes there and later back. It is no a major issue despite car being... quite tight.
Doing makeup in vanity mirror? - my mileage varies but it still better to have just cover and some lipstick, not that I can do much more on my own right now.
But putting on your breast forms that have been riding in the trunk (that is not heated as it is separated from passenger space) while it is 10 Fahrenheit outside is a thing to remember for quite some time.