Back when I learned flyfishing, 3 wet flies was a common method in PA streams. These were the traditional wetflies too with the duck quill wings. If your leader is tapered properly then it's relatively easy to cast with 3 flies. Just don't cast for distance and make sure you have a big loop in your line.

Also multiple fish on the line is not the thrill you think it is. Usually it's a wet blanket feel. I had two 3 pounders on once. One would try and jump and the other would snub him down.

It's an old style meat way of fishing. Very effective too.