Safety first. If the river looks too risky, turn back. I've spent years whitewater canoeing across Canada, so much of what we attempted on ATV was buttressed with this experience. Know your bike. Know the river. And consider all the risks carefully. Take precautions such as double or triple dry-bagging your survival equipment and sat phone. But no matter what you do, if you think it's too risky, it is. No adventure is worth an emergency evacuation or worse. Stay safe out there.