The reason I mentioned the version of 5-1 I coached against is I equate a 3 front with a down nose guard. In the 5-1 if the nose guard is down he will have harder time staying with his man if he releases, ie the guard in an unbalance line, thus all I have ever seen is the middle man up. Do know when Clawson ran it at PC, his one was hell of a safety who also went to state track meet in 200 meters.
The play you describe has been run a bunch against 5-1. Harvey Wellman told me about it and scored on Clawson with it. ha