Well I don’t live in any certain neighborhood or town that doesn’t allow you to park trailers outside. That’s in places like Saint Augustine. I’m not really worried about anything like that.
Just because the allow the trailers in a residential area doesn't (necessarily) mean they'll allow a wrapped one- which often makes it fall into a commercial vehicle or advertising category that many don't allow. Best to check your local ordinances.
Many others have made the important points, though, regarding your idea- among them, it's not a great idea to put your valuable equipment into a trailer (unless you're talking a container-type trailer with airshocks, etc., to mitigate rough rides), the flea market thing is time consuming precisely because of the browsers/talkers, the abundance of quickie shops, etc.
So yeah, use your trailer for equipment storage and your installs. If your area allows it, wrap it (or at least put a name and number/website on it)- and make sure you use hi-performance materials that last. Nothing will be more off putting to a potential customer than a sign shop with bad graphics or a vehicle wrap or vinyl that's peeling, fading, etc.
Good luck.