The name of the game is CHEAT! Just like baseball, you can choke up on the bat. In our case, we simply throw across in a narrow spot and walk up or down to the desired location. Another way to cheat is shorten the throw via wading out to a safe mideam location. A snag line or tethered swimmer is another way to shorten the distance. If trees or boulders are in the way, cross higher or lower and move to the desired point in the stream. It always helps to have a receiver (or two) on the other side. Once the line touches the water surface, it typically moves quickly downstream. Do whatever you can to keep the line high and out of the current. This often requires starting up the river bank, perhaps feed from a tree. A canoe or raft can hold an extra person that can concentrate on keeping the line out of the water. If feeding from shore, the boat can tape or tie on the end of a paddle to reach even higher - like a flag mast.
Whenever working with lines that cross a river, rescuers need a rescue knife or trauma shears. Also, warn upstream boaters that it isn't safe to go downstream. Place persons with throw lines downstream and have safety sweep boaters downstream as well. People that are focused on the rescue instead of where they are going may flip - be prepared.