Did some searching on the net for feedback on paint protection films. The highline car guys spoke highly of product called Ventureshield; better resistance to yellowing, and no slight orange peel effect as reported for 3M film. I called the manufacturer this AM to discuss the application.
No problem going on over polished aluminum; the Harley guys are already doing it. The factory fellow says it will not totally block the atmosphere and eliminate surface corrosion and tarnish, because it is more porous than a properly applied paint film. However, compared to bare polished aluminum, he says it will reduce the corrosion/re-polish requirement by 90% or so. The happy trade is resistance to foreign object damage, meaning bugs, scratches, and anything the prop may blow against the leg. The film may be removed at will if re-polishing is necessary or if the surface of the film is damaged.
I was referred to their distributor, who offered to send enough sample material to cover my gear legs; interested new market for him. I'll give it a try and report back here.
As a side note, this stuff would be a nice addition for standard Van's fiberglass gear leg fairings or painted Grove legs. It may stretch over the nose of a wheel pant too. Apparently there is a rapidly developing network of professional installers in major markets. Anybody for chip-proof legs and pants?