This is the ultimate Ring Road Adventure.
You can either do this tour by staying at hotels around Iceland - or rent a camper van.
Here’s a link to the best guys for renting a camper van —> RENT.IS
Here’s a link to the best guys for renting a car —> BLUE CAR RENTAL
In the wintertime, I suggest getting a 4x4 but all can be done in a regular vehicle which is also a lot cheaper.
I usually recommend starting with the South Coast and traveling counter-clock wise around Iceland. This will ensure that you have enough time to explore the highlights on the South Coast and adjust your itinerary if needed.