Ishigaki and Iriomote + surrounding islands – car vs scooter price equal for 2 people?

I'm planning on arriving on a Thursday morning and leaving Sunday evening and looking at transportation options + day-level itinerary. I'm planning on Ishigaki being the home base.

• Day 1 – Arrive in morning and ferry to Taketomi and Kohama – hire bicycles for transport

• Day 2 – Ferry to Iriomote – hire scooter or car

• Day 3 – Ferry to Kuroshima and Hateruma – hire bicycles

• Day 4 – Ishigaki – Hire scooter or car then leave to airport in the evening

For Ishigaki and Iriomote – I'm looking at 50cc scooters from GoShare which are ¥5,500/24 hours. The thing is a car is ~¥11,000/24 hours and I'm sharing with someone else so it's the same price + we have luggage. I've never ridden a scooter before but given that situation, is it better to hire a car? Whether for weather exposure or safety reasons? Like roads are narrow in north Ishigaki so a scooter is better or more convenient.

I would want to explore as much of Iriomote and Ishigaki as possible within a day each. So realistically, I'd be hiring on Day 2 and Day 4 only.

Thank you!