Hi Rich,
Thanks, I appreciate the compliment.
As for after polish care; the goal here is to slow down the inevitable - reoxidation. You can use a Polish/Sealer from Rolite or Walbernize, but if you just wash it a couple of times a year, and every other year just do a polish job with Nuvite 'S' (final stage polishing) using a Cyclo polisher and cloth, you'll be ok.
Airstream puts a clear coat over their new trailers, but that is over newly installed aluminum, not polished aluminum. In painting, I never go past 400 grit, I feel I need that for the paint to stick. I can't imagine trying to clear coat 'polished' aluminum, note; I work it out to 1200 grit prior to polishing.
Thinking about it, you might get a satisfactory finish if you sanded it out to 600 grit and then clear coated the the trailer, but by the time you've worked it out that far, why not go all the way and polish it.
Dave