This is one area where we have huge advantages over professional rescue personnel. Strong boaters can pretty much place their boats almost anywhere on the river and get very close to a victim. Often, the challenge is getting out in a safe manner so you can apply leverage. Boaters may be tempted to tow swamped boats which is fine only if you have a quick release system. A flipped boat is also a dynamite flotation device providing far more flotation than your PFD.
In a number of rescues, response time is critical. Often, paddling directly to the victim is the fastest way to get there and start the rescue effort. Strong boaters can pretty much put their boat anywhere in a rapid or at least get close enough to rock hop in a few minutes. All of us carry throw ropes (or should). Many also carry carabineers and perhaps a pulley or two. Throwing a rope from the accident site is often easier than from shore. For one thing all you need is distance, accuracy doesn't matter. Large craft like canoes and rafts make an excellent and safe platform for rescue activities. They can also be used to haul out an injured boater. The boat in skilled hands is a very versatile tool.
Instructors need to be proficient paddlers to be effective in rescues. Practice your rolls, eddies, ferries, and use of water features at your favorite paddling venues. Although less common, the SWR course is perfectly suitable for boats other than kayaks. Other boats like rafts and canoes are actually better rescue platforms which is why all fire departments mandate the use of various types of rafts/inflatable's. I have even had requests from standup paddleboard instructors for this training. You need to know the strengths and weaknesses in regards to rescue for various craft. When teaching, it isn't a bad idea to include a variety of craft if possible.