Hi Tony
I'm a firm believer that a stern anchor, even a "mobile" one, or a big "mud weight" that can be thrown over the stern on a decent length of rope or chain, is a good idea for just about any boat on a river.
Why? If there is anything like a flow on the water, when traveling downstream, deployment of a bow anchor can create a very scary situation.
If the anchor bites, then inertia of the boat + current will cause the stern to swing in a circle the diameter of anchor rode and hull length.
This can be rapid and violent, being:
1. Alarming to those onboard.
2. Dangerous, especially if the vessel hits another or a solid object.
Deploying a stern anchor, even if it doesn't stop forward movement, will slow the vessel enough to reduce the effects of deployment of the bow anchor to a hopefully manageable extent.
If a stern anchor is not available, if at all possible turn to head into the flow before deploying the bow anchor.
Just a thought
Paul Hayes