Checking locations out is a must in the modern age. But that said you can introduce some risk reduction. Leave another set of clothes in the stairwell on the floor you are planning on taking the lift to. Sure I’m said this about walks outdoors too, if your going on a circular walk just leave some clothes half way round so you have two options to getmto some clothes.
If you want to make it more fun leave just underwear or something sexy but make sure it covers properly.
Reading some of the naked rambler websites a lot of their walkers take a wrap skirt as they are very quick to put on.when out walking with boots on. Would add a very different element to a walk back down the stairs if you had to use it!