I can't quite visualize where this is on the boat. Don't be offended but I think it looks like a real hack job. The fire extinguisher is mounted to the removable bracket? The mate for the bracket is mounted to the aluminum tubing? All of of this is exposed to the sun and salt water?
The clamps should be insulated from the tubing otherwise they will scratch it and you don't want stainless in contact with aluminum. Ancor has a rubber insulated stainless clamp. Would look better than a hose clamp. Not sure what to do around the extinguisher.
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Mine is mounted at the helm, lower right outboard side. Bracket came with the extinguisher.