Spa Day Question - Is it possible?

I already have several small businesses on community lots, like in the basement of a mall or a corner of the park. I like the idea that my active sim can go there to do their services or pretend they work there (say freelance writer or stylist). I play those rooms mostly with the working sim, not a big deal to me that I can't go there as a customer and buy the service. I don't think doors can be locked on community lots, but you could always (re)move the door in BB mode, to stop other sims from using the facilities when your "owning" sim is not there.