Actually, I had been jokingly thinking of something similar. If I were to try this, I would also need to warn people not to stand directly behind either cleat, since if the line had any flex it could fling like a bungee cord. Another potential problem is if the manufacturer of the line reports 50 lb breaking strength, but actually has built in a "safety factor" to account for deterioration over time, and the actual strength of new line is 200 lb.
The actually breaking strength would be easy to check.
A tree limb and a couple of weights from a weight set.
I was also thinking that on the boat end one of the rubber snubber cords where you wrap your dock line around a long rubber tube would give it more of a yank than a snap.
The snap back would be minimal as their would be no weight at the dock end of the line. They did a test of this on myth busters and it was not as much of an effect as expected.
Also you could put the dock line on the west side of the finger pier to give you a couple more degrees angle.
The real challenge would be to have the cahunas to come blasting out fast enough so that the angles would work out. If the stern gets blown west too much and you have no angle you would have no effect.
I can't belive we are talking seriously about this.
You are only 4 hours away from CT what weekend do you have in mind?
In fact we just invented a whole new genre of sailnet videos.
We travel to each others boats and do stuff we would never have the nerve to do on our own and really push the envelope of sailing.
Call it sailnutter.com