Is it just set decoration or is it used in the scene? Referred to by the actors?
In the movie "Dickie Roberts: Former Child Star" they used a slip n slide, and even used it incorrectly without water and the actor got all scraped up. Wham-O sued Paramount Pictures and lost. That was a victory for ALL filmmakers like yourself.
The flip side is that Playboy could file a groundless lawsuit and you would not be able to recoup your legal fees even if you won.
I would never ask for permission. It just gives them the heads up.
One option is to digitally cover it up with Adobe After Effects. I've done a lot of that type of work and it's not difficult to do if it's far enough in the background. http://www.insaneasound.com/motiongraphics.htm