I have superb sea views and no garage and have done for twenty three years. Cars are covered in salt after a ‘Blow’ With a bi-yearly wax and some attention to rubber occasionally, we haven’t suffered cosmetic damage.
What does get eaten at without any annual refresh of Waxoil et all is the underneath of the car.
Soft fitted inner…… https://www.specialisedcovers.com/search/?q=Mazda+Mx5 to get you started
If you want to cover over the top in a windy area like ours you need not just a top cover but also a soft undergarment too and lots of straps so the whole cover doesn’t move.
A high quality cover came with our car but I’m leery about using it TBH.