You have different rules and such with regard's to mailbox construction and liability issues.

Mailboxes get wiped out all the time around here due to snow and ice, and the fact that the gal with the cell phone stuck to her face can't multitask in these conditions.

I have a bunch of 4" schedule 80 structural pipe, that I was going to make 7' long mailbox posts for a number of us in this area. Nope! If a Honda Civic hit one of these and someone was injured, that would be a lawsuit. Only can use wood post's that easily shear off.

I would also be cautious of strapping a winch on a utility pole. The utility pole is not yours to do with what you want to. It belongs to the utility, and for their specific purpose. That could also be a major lawsuit.