I do not think using a PO Box would be a problem. It isn’t for me. I have a PO Box for all of my official mail. I only use the location address when ordering things to be delivered that can’t go to the Post Office. I do not list my location on my website. I don’t want people just popping in as it interrupts client sessions. And I prefer to prescreen clients over the phone to save me time. As of right now, the studio is a trainer session facility only (no working out without a trainer). I do plan to expand to a open door gym sometime in the next year. When I do that, I will put the location out publicly in my ads and website.
I had a open door gym years ago that I ran the same way. First as a trainer session only studio and then as an open door gym. But I put the location on all my ads the entire time. It was not productive to have people just pop in to see the facility while it was a trainer only studio. That is why I am doing it differently this time. And it is working out very nicely for me. People call that are interested and I set up a time to meet with them according to my schedule. Before people would pop in. Most of them were at the building to go to another business and saw my sign. They came in, took some information as I was busy with a client, left and never got back to me. I may have lost a few potential clients that were looking for a location to visit unannounced, but it wasn’t an issue. I had all the business I wanted to have.