So, how long will it take?

I'll be staying in Volcano, and want to explore. A big loop of the island would be great, if I can do it in a day. I have another day planned up on the volcano.

And, if I can, what stops/sidetrips should I consider? The rental agency says I can't go on "Saddle Road". Is this a big problem? I'll be there the 3rd week of October.

Thanks!

JP