I had a BBQ trailer that I operated in Florida for a few years. It had everything I needed, screens, sinks refrig etc, so the health department required only that I had a legal comissary to dump my gray water and fill my fresh water. I found a local septic sucking guy and paid him by the dump.
They weren’t very forthcoming with that info though, until I figured it out. Meanwhile I spent a month trying to find someone with a full kitchen to help me. Nobody has any incentive to help you, unless it’s an old friend. You will immediately become their competitor.
What I ended up with was a Mobile Food Dispensing Vehicle License from the state, which meant that in theory, I could operate anywhere in Florida, subject to local ordinances. That’s where the problem came. Most towns don’t want trailers and carts messing with their big tax base restaurants . I was also legal for any festivals.