You may be surprised in comparing your winter in warm temps or staying home in bitter cold.
Yes, you'll have a vehicle fuel bill to get you down to Florida but once there you won't be spending any more than you would at home running around.
Food is needed at either place. That's an easy one to control.
What is your heating bill at home in the winter. That will be offset by staying in warmth.
As far as the RV, but a used one at first and see how you like it.
As stated, your health will be better and you'll be exercising more in the warmth. You'll also be more social and perhaps learn new activities.
You'll love it!!!