I have not found a state in the US (including FL) that I have had any issue booking a spot on a charter boat as a solo diver.
I always call in person, tell them that I am coming without a buddy, and ask if that is an issue. I have never been told that was an issue, and I have always been buddied up once I was on the charter.
To further place your mind at ease, I’m a guy. I guarantee if you solo sign up on a charter boat guys will be tripping over their fins volunteering to be your buddy:)
Have fun!