If you decide to go to Porto Santo you have yo rent an ATV. It's super fun and the only true way to get around the island as it will allow you to cross pretty much any path that a car or scooter otherwise wouldn't allow.

We used this place and had a good experience. We paid 50€ for 24 hours, which is pretty cheap in our opinion since the ATV fits two people.

Watch our video of driving ATV on Porto Santo: https://youtu.be/_sR2vJ6sT5M?t=302