Thanks for your contribution to the cause.
You've submitted to jurisdiction in Florida, by hiring an attorney to appear in court for a reason other than to challenge personal jurisdiction. Even if you didn't mean to do this, the attorney's appearance binds you to the jurisdiction.
You will not be able to resist registration of the judgment in California. And, if it's too late to appeal in Florida, then your only recourse (other than bankruptcy) would be to sue the Florida attorney for malpractice.
And, the statute of limitations for that is two years -- so your time is running out fast.
Once again, if this deal was between the plaintiff and a separate legal entity (e.g., LLC, Corporation), and not with you personally, then you may be able to just shutter the doors on the current business and start a new business -- thereby making collection effectively impossible. You would not even have to file for bankruptcy with the LLC/Inc. You just finish your existing business and meanwhile start doing business under a new LLC/Inc. The plaintiff won't be able to get any assests beyond whatever remains in the old LLC/Inc. And, if you're paying yourself a salary to manage the business, you can extract most of the assets as payroll, and leave the LLC/Inc. an empty shell.
But, if the deal was between you personally and the plaintiff, then you could have a lot of difficulties unless most of your assets are exempt -- and the cheapest way out may be to try to settle for a lesser amount and put the matter behind you as fast as possible.
Hope this helps.