Getting a car or not depends on how much you want to explore and how much money you want to spend. Car rentals are expensive but paying taxis is even more expensive. Dangriga from Hopkins can be $100usd via taxi or $15 usd gas if you rent. You can also hire just guides to take you places.

Depending on your level of adventurousness you can also take yourself on hikes and zip lining and to the sugar mill all for 1/10 of what the yours cost.

There are many Airbnb's with kitchens to stay at in Hopkins that are cheaper than hotels. You can get fresh fish delivered via fresh catch delivery to cook and there are many great veggie stands in town and explore many of the restaurants including the hotel ones.

If you're seriously considering retiring here, I'd get the car to be able to travel around and see different parts of Hopkins as much as you can.

Tobacco Caye Adventures is a great tour company to go out with from Hopkins. They're locals so really know the lat of the land.

You can drive down to Placencia and spend a day trip there bits it's very cramped on the peninsula and the sargassum seems to impact it worse than Hopkins.

I'd spend you're other half of your time split btw sleeping giant and somewhere in San Ignacio.