Can you afford a small window AC unit and just cool one room? Hang curtains or plastic and/or close doors to other rooms? This might ease the burden and keep you cooler for less money. Sitting all day in almost 90 degrees is probably not safe.
Or are you eligible for low-income housing maybe in a smaller town but with adequate medical care?
This all sounds pretty desperate.
If you have exhausted all of your other options, and at
72 years old, you have become a 'hostage' of sorts....and if you want the freedom of the road, you need to take action unless you want to see yourself going further downhill.
If your health is good and you can move around adequately, I would think about selling off everything you can, like furniture and other stuff to make a few more $$$.
Then let the electric bill and other utility and rent bills go unpaid for a month or 2 (or make very minimal payments), and use all of your saved money to buy canned food (or go to the local food banks) and then buy a very small, cheap, used, enclosed trailer, (or a harbor freight trailer with a couple of totes strapped on it) pack it with what you really need, (clothes, canned food, water, supplies, etc)...then hitch that trailer to your car (which hopefully is reliable) and head north toward cooler weather and the open road and let what happens to the mobile home, happen.
You can rendezvous with other nomads farther northwest, and if you are frugal the first few months, 'car dwelling' on free lands, national forests, and Walmarts, in a short while your account will start to grow and you can begin to have hope for a better future.
You can always return to Florida in the cooler months for any needed medical issues or doctor appointments.
Come, dance under the moon, Moondancer!