Stainless flag pole

Take measurements of the holder and take pole into a stainless man who could either polish off a small amount thus keeping rust free, or get him to weld a smaller section to the end of the pole, either way dead cheap
 
If I spent 40 pounds on an item that was the wrong size, I would typically return to the shop, and exchange it for the correct model, I would not buy a lathe, or a sander and rub away for Britain
 
I was under the impression that stainless steel needed to be polished to remain corrosion free in a damp environment so sanding would not be a good idea. Am I wrong?
 
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