I have been giving this some thought too, mostly swaying to doing nothing to the bare aluminum. Then I saw the Lizardskin ceremic which might have some use but I would like to know what it's like before gettting 2 gals of it. The finish of the Aluminum is very durable as manufactured since the surfaces are worked from the rollers at manufacture time. The weld area is my guess as to the least protected.
I'll bet if Rob did the test on sanded sheet the test might have been different. I have a Herb Adam VSE cobra that uses basically the same aluminum construction as the RCR 40 and it has been in and out of my garage for about 6 years with not much change. Hauled it back in the rain, etc.
Do nothing, clean and do a Lemon Fresh Pledge treatment.
A couple of thoughts, I had was some of the aircraft (yellow and green) primers that you can get in Epoxy, Zinc Chromate, and the more human friendly Zinc oxide. And no likely leave as the top cote. Aircraft Spruce has them, not inexpensive, but durable looking stuff.
Lizardskin if not a thick bed liner like material. The ceremic version seems to be safe for high temps as well as 'Class A Flame resistant' (not sure what that means). This might have some heat proofing value, but can't find much on the web other then some testimonials that were on their site so they can be somewhat discounted. Looks pretty good, would be nice to get a pint and give it a try. Will see how it works out on Jonathan's car. Looks pretty good. Some interesting comments on the Factory 5 list, but still not too much. It is easy to get as Summit Racing has it and the gun now on the site.
Lastly Zolatone, they have some nice coatings but lots of work and no info on temp capability. Might be funky looking, but I have always like the speckle trunk paint
Sandy