A 8 1/2' to 9' pontoon boat works good on rivers. It's not too big for controlling withn fins and many of them are big enough to handle up to class II fairly easily .. Mine is a Water Skeeter low profile.. has an electric motor mount and an anchor. I can carry 9' oars, a cooler, extra gear, large net, stripping basket and two fly rods.
Depending on the river, I usually fish from it and and can effectively guide it and keep it oriented in the direction I want by finning and have both hands free for fly fishing. You just have to keep aware of what's ahead of you and be prepared to go to the oars as needed which is easy to do On some rivers..especially the ones with curves, fast currents, sweeps, rapids, big rocks, etc., I just use the boat with oars for transportation from one place to the next and get out an wade. The fins I have fit over my boots and are easy off - easy on.
I usually fish with a friend. Rather than having a two man raft where someone has to row and can't fish, we use our pontoons and stay fairly close together and use walkie talkies as well. We can haul two in the bed of a full size pick up for shuttling..don't need a trailer. Or, if I'm fishing alone, I just hire a shuttle service...many rivers that are floated often have that service available.
It also works very well on lakes as a kick boat.
Hope this is helpfull.