Bushwalk Australia

I'm thinking of taking my canoe up to the Murray in a couple of weeks with a mate. In order to avoid a car shuffle I'm thinking of doing a couple of days in each direction. Either from Peechelba down the Ovens and then upstream on the Murray and then back again or just on the Murray starting at Bundalong up and back.
Anyone know how hard upstream paddling is along these stretches?
I've only done an hour or two on these stretches before so I'm not sure how a sustained, day or two long paddle would be.