Regarding having sex in public at the adult store, I've done that. I've always gotten a kick out of gloryholes and being a theater slut. We used to frequent an adult store that had a paid private play area in the back. It also had a gated parking area surrounded by a privacy fence for paying customers. I used to love being naked out there and getting fucked in the car or bent over the hood of it but I've always been a bit of an exhibitionist.
There are a couple things that you should consider before doing something like that. First, you can be charged with a crime and end up registering as a sex offender if you get caught. It would definitely be much riskier if the store is in a high traffic area, lacks a fence, etc.
Second, are you intending to be the only one having sex with your wife? You will attract a crowd and men can get rather pushy at those sort of places. Most will walk away if told no and if they don't you can generally count on some help from other patrons and staff if you are playing in the building. Outside you will be somewhat more exposed and further from help. This is less of a problem for me as I expect to service a lot of men when I go and don't turn anyone away as long as they are clean, patient and willing to practice safe sex. If you or your wife aren't comfortable with her fucking or at the least sucking a couple other men after your show it might not be a good idea.
My husband ran a trucking company for years and we love taking long road trips out west. I've spent a lot of time eating up the miles naked in the car flashing truck drivers. Much of the time I recline my seat and put my legs up on the dash to give them a full body view. I keep a vibe handy in the glove box and spend a lot of time toying myself as well. Hubby knew all the carriers and would have me give the best shows to the drivers he knew where out on extend trips far from home and family. They can get pretty lonely and seemed to appreciate it more. Again it's a pretty big thrill but there is that pesky sex offender registry to worry about these days. Also, there has been a big push in the industry in recent years to recruit foreign drivers. A lot of them (especially middle easterners) won't appreciate your efforts and may well be insulted.
Good luck!