Easy to walk from Running Creek to Tobacco in a day. No big climbs. Good foot pad/track although blackberries may be pushing in in a couple of spots.
Kids, depending on age, could be a bit weary at the end of the day.
I'm always a little unsure when people refer to two tracks. I know of only one. It is possible to follow bits of the river bed, but calling that option a track is wee bit optimistic in my opinion.
The main foot track runs on the true left of the river, comes close to the river in places, and swings 100 to 200 metres away from it in others. This track finishes at Wares Flat, where it intersects the 4wd track/road which comes down from Fry's and then climbs up onto the ridge above the Howqua.
You can follow the 4wd track for the k or so to Tobacco, or wander up the river flats, crossing the river if it's low enough. Much of Tobacco (and Wares for that matter) is private property, but you shouldn't have any difficulty finding a suitable camp site. The true right of the river, between Ware's and Tobacco, is popular for camping.
That bit of country sees a lot of activity hunting deer with trailing hounds, but the season for that has now closed, which should make your weekend somewhat quieter