Adelaide to Melbourne via great ocean road

I have a friend coming out next year from the UK and we're thinking of doing the Great Ocean Road with her.
We'll be traveling with a 5yo, 3yo and 8mo. Realistically how many nights would you take to do it? Ie how many stops?

The main problem is we won't all fit in the one car, so DH reckons we take both cars so we can take the camping gear. But I'm not keen on that idea. So the other options are hire a minivan, but there will be no room for camping gear so will have to stay in motels, or hire a campervan, and camp. I'm liking the idea of a campervan but we'll have to go a deluxe model to fit in the 3 car seats. Which is exxy, so I'm trying to gauge how many nights we might need it for.

Any ideas? Tips? Experience?

I recently drove from Adelaide to Warrnambool with a nearly 5 year old and a 2.5 year old.

I stopped in Robe on the way so about 3.5 hours each day. My kids were great on the trip but they are seasoned 'long' distance drivers, they have been doing a 3 hour drive to visit family every couple of months their whole lives. In earlier days, when I started doing long drives they were appalling at about the two hour mark. Two hours was their tolerance and then I would get whining and winging. I seem to have hit a good spot with their age at the moment and they did cope with the longer drive this time, but I would be unwilling to push a drive further unless I had to. If I had to do a long trip, I would have to break it up with a few stops at parks etc along the way and then the day of travel is just sooo long! I prefer to do a stretch, pull into a town and stay the afternoon/night so the kids enjoy the experience a bit more. This would make the drive between Adelaide and Melbourne a long one though!