How to include Yakushima in Kyushu trip

Hi!

I will be flying into Kyushu via Fukuoka and plan to do a self drive 2 weeks trip. This should cover the following areas:

Fukuoka
Nagasaki
Kumamoto
Oita
Takachiho
Kagoshima / Kirishima / Yakushima

Highlight of the trip would be Yakushima. If short of time, I'm willing to skip places such as castles and volcanoes. I prefer to drive (road trips) when visiting attractions, unless it's just travel from point-to-point.

I need help in deciding how to include Yakushima into the whole self-drive itinerary.

(a) Is it troublesome to fly into Fukuoka, rent a car, visit some places then drive to Kagoshima, return car. Ferry to Yakushima (definitely self-drive there). After Yakushima, ferry back to Kagoshima then rent a car again back to Fukuoka?

(b) Or should I take the train right after arriving at Fukuoka to Kagoshima, and visit Yakushima first? Then ferry back to Kagoshima where I rent a car for the rest of the journey?

Flying back to Fukuoka from Yakushima is out of the question as I would like to do some shopping in Fukuoka before going home...

You might be able to negotiate with the rental company under option (a) to avoid one-way drop-off penalties. But either option looks ok. Option (b) gives you more sightseeing time.

You can drive around Yakushima twice in one day - making brief stops to see stuff, assuming you are not hiking. Also beware - the speed limits are strictly enforced.