Personally I would be hesitant to try Penthouse outcall service. Here on PERB, there's hardly any good reviews of any of the ladies, with the exception of Savannah. Overpricing and lackluster service are the common themes.
I understand that you are not interested in incalls, but the ugly reality is that Edmonton is a MP town. If discretion is what are you concerned about, why don't you contact an SP that you are interested in to have something worked out?
There are going to be slow times at MPs. Many good SPs will take the extra effort to minimize patrons from encountering one another. Certain MPs have discrete rear entrances. You can wear a hat/ sunglasses if necessary.
If I am wrong about your concerns for privacy, then I'll apologize in advance. But based on your posting history, that's the notion I am getting.