We stayed at the K On M caravan park a few years back on a pay 5 stay 7 special. Its a nice tidy CP near the river.
It made a good base to explore the area.
Any free camping along the river in Winter has a high risk element to it because of the slippery grey clay.
We enjoyed lunch at the nearby Banrock Station winery.
If you enjoy wine go to the Berri winery, bargains galore!
We also stayed at the Lyrup Ferry Campground & enjoyed visiting the almond nut outlet nearby.
Don't forget the roadside stalls around the area selling in season citrus.
Its a lovely area, enjoy.