I did it in Boulder , CO for a few months. I didn’t have an address but I did have a cell phone and debit (not credit) card. I did look and smell like a campfire. I’ve never heard of a deposit for a gym- those must be some fancy gymnasiums.
I just checked because it’s been a few years. The building is now occupied by 24 Hour Fitness, but I don’t think that was the name of it when I used it.
If gyms are cracking down on this use case then that is a shame.
I wonder if you could retro-fit a 53’ tractor trailer into shower(s) + laundry stall(s) on wheels and bring it close to the “customer”? I wonder how that could work.