All threaded forks are fitted to the length of the headtube, one off or not. I would think that that many spacers could lead to a bent steerer and/or ovalized headtube. I remember hearing the rule of thumb is 1 1/5 times the steerer diameter, but that might be a bit conservative. Most bike shops can cut the threads on your steerer down to to a level so it can be cut to fit your bike.