Re: Alum highway pole for mast
A local boatbuilder, with much the same type of philosophy as our own Brent Swain, used to write a column on economy boatbuilding in Pacific Yachting back in the heyday of home building. He advocated this very thing - the light poles were MUCH cheaper than mast extrusions since they were produced in such huge volumes.
He simply screwed or riveted an external track on them and used sail slugs.
Personally I'd go for a round one, not one of the faceted ones.
I, myself, personally intend to continue being outspoken and opinionated, intolerant of all fanatics, fools and ignoramuses, deeply suspicious of all those who have "found the answer" and on my bad days, downright rude.