I'm trying to think that one through, which is hard when the caffiene is gone for the day. The only real purpose of that spring line is to prevent the boat from going forward, while allowing it to rotate, right?
It would seem that you could do the same thing from the sten and midships positions, leading a line from the stern (where you remain) forward to a midships cleat on the dock, and BACK to you, perhaps paying out some line to allow your stern to swing out, but keeping enough tension on it to prevent forward motion. And, if you can get the boat rotating that way, then you may be able to let go the bitter end and just haul in the end that was secured on your stern cleat--retrieving the line without leaving the helm, or letting it get anywhere near the prop.
I must concede I'm not the master of spring lines, but I do pretty well with making sure lines come back to me, so I can always cast off without stepping off the boat, or tie up without jumping to the dock, etc. (Only time that didn't work was up in British Columbia, where horn cleats seem to be illegal or unknown.)