My question is.... can these aluminum tanks be brought up to a shinny finish like we plan for "MoonBeams" skin?
Yes, the tanks can be polished and will take on a shine much as the Worthington tanks on my Overlander pictured below:
The Ruth's (P and S Trailer Service, Helena, Ohio) started out a pair of brand new tanks when they polished my Overlander; but the results can be just as good with your originals - - the only type of issue that polishing cannot solve is severe scrape type damage that will still be visible after polishing. There will obviously need to be precautions taken when attempting the procedure with tanks that have been used, but I have seen the process undertaken by Bill Scott (on a 1966
aluminum tank) during a demonstration on the Wagon Wheels Caravan in 1999.
As a side note, you will want to be sure that your propane service technician is aware that the aluminum tanks require an OPD valve with a dip-tube of a different length than similarly sized steel tanks.
Good luck with your tank refitting/certification!