Great advice, I'm following this as well. First time out today and I only managed a good anchor a couple times. Seahawk 4 with a small grapple and a sand-filled gallon jug as a second. Grapple too light, line was too short, nor any chain on board. Even when anchored we swung around a lot, but it worked for fishing a spot. Brought up huge seaweed clumps when we hauled it up, because we mostly just dragged the grapple around.
I'd guess a big grapple with chain and much rope for that emergency stop. If you not in such dire straights you're able to drop anchor, you may be able to keep a hand on the line till you feel it catching and tie it off to halt further drifting. My worry would be currents swinging me into the banks to where I might not want the boat to contact shore. Depends on the river I suppose. Use the oar as a pole if need be.
I piloted us into a low-hanging leaning tree today near the lake banks. Wife had to help fight and push off from the branches while I quit trying to remove a lure and pay attention! All too easy to float astray if not watching, let alone fighting current and a dead motor.