Problem is that the car is not registered and I cannot get a temp tag for it
How much of a risk taker are you?
How bad would the consequences be if you got caught driving the car unregistered? If you did it at night, chances are quite small that you would come to the attention of any law enforcement people. I'm guessing (just guessing, mind you) that you would be looking at a $50-$75 fine as a worst case scenario if you got caught.
Of course, Florida may be different from Alaska as far as license plates go. In Alaska, you buy a car, register it and put the plates on it, and those plates stay on the car for life. You sell the car, the plates stay with it. My faithful old Land Cruiser snow plow truck has plates on it that are 36 years old.
If the Miata has no license plates on it at all, then it will be a lot more obvious that it is unregistered and your chances of being apprehended will be greatly increased.
tanstaafl.
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"There Ain't No Such Thing As A Free Lunch"