I'd suggest you do a lot of research before you invest anything into this.
Unless you have a nice trust fund to rely on or have enough relatives to keep you booked, you need to figure out how you are going to get customers to your boat. You could of course, put your boat on charter boat row at about 5 grand a month, or perhaps get enough business from a web site to pay your expenses, though neither ia a likely scenario.
What are you going to offer your clients that the other, established boats, can not? You can't really undercut the locals as they might take a very dim view of that. It sounds as though you have little to no experience, so starting off on your own boat as captain could be the road to financial disaster. Remember, Miami is a prime tourist destination in the winter, but a hot, muggy, windless (for the most part) place in the summer. This leaves you with little to no income for a bit more than half the year.
I had years of charter experience before I sailed my own boat to the Eastern Caribbean to start a charter business. Though I knew the area well from years of being there as captain on other people's boats, my wife and I did something like ten trips from Grenada to the VI, compiling out of the way anchorages and looking for a niche where we had little competition.
We got lucky and found a very small niche where the sailing was easy and the distances short. We also stayed away from high end charters, and considered the cost of transportation to and from the Caribbean, for our mostly European middle class clientele. We got very good at charades. The American market was saturated with 6k plus a week boats and we had no desire to try and join that crowd. So, we charged about half that and stayed as busy as we wanted to be. Our business literally died in a week, when the Covid epidemic became a world wide pandemic.
Good luck and I wish you the best, but it is going to take a lot more than a six-pack ticket and a boat to be successful in the charter game, unfortunately.