I'm in the navy, but since I'm an electronics technician no one thinks twice about me vaping in the shop, they're use to me having gadgets and ..... I find that if I hold the whole 510 in my fist and take a drag, I can vape anywhere I want. I just hold it in long enough that when I breathe out, there's no mist. Helps rebuild my lung capacity too.
I have actually done it while standing OOD on the mid watch. But for me I usually stick with any unoccupied stall. Or a fanroom. LOL