Self drive with kids

From utoro in shiretoko , I pls not drive to sounkyu Onsen with my two kids, 9 and 7. Is it too far , I hope to drive for 2.5 hours a day, max. Should I go to sbashiri first and break my trio, staying there overnight?

From sounkyu, I plan to drive to furano. How long is that? Or should I stop somewhere for the night first?

Thanks
Eric

I estimate the drive to take 5 hours, not including breaks. So, if you try not to drive more than 2.5 hours per day, you better split it into two.

I did the drive once and we spent the night in Kitami half way. However, there is not much to do there. We just slept there.