Bairnsdale is a solid 3.5 to four hours. Unless you have luck and your kids fall asleep, I wouldn't try doing it all at once. The stretch from sale to bairnsdale is so damn boring, and with nowhere to stop! once you hit the freeway on the way out, you could probably do traralgon pretty easily. It's about two hours. Any more than that and you'll be pushing it to keep kids happy

Tgon has maccas adjacent to a shooing centre right on the highway in the kiddie of town. Directly across the road is Victory park. Plenty of running room. There is also Newman park down behind that Park - plenty of play equipment only a couple of minutes off the highway.

Beyond that, the next major centre is sale (rosedale is in between - there is a park but it's on the other side of the road and parking can be an issue sometimes). If you get past traralgon without a stop, do yourself and your sanity a favour and stop somewhere in sale (you can go past the turn highway turn off/roundabout a few hundred metres and get to park land at lake Guthrie)

Past bairnsdale you'll have lakes entrance. Stop there cis not much else directly on the highway past there until you get to cann river. Great park there for stopping and burning energy.

Once you get past there I'm not much help cos I usually turn off to head to Canberra up the cann valley highway rather than going up ther Coast.

My biggest advice is to make sure you've had a rest stop at either sale or traralgon. The stretch from sale to Bairnsdale is horribly boring. There is only maybe one stop (at the Billabong roadhouse). It's ok for a pee break but I wouldn't expect anything more of it than - too many cars/trucks and no where for kids to play