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I've seen this problem in a more sneaky fashion, where they draw the barrels (18" diameter) on the outside of the 12-ft shift, so you are really shifting 13.5 feet. Be aware of you see that.
I'm checking out now. Wife's car died so I have an unplanned day off today. Just relaxing and buzzing through my notes.
Best of luck everyone. Thanks for all your help over the past few months.