I used bar keepers friend for bad oxidation, very mild abrasive (like dust) and wood bleach. Tooth brush will do the seam and clean off worst of the patina. I think soft rag such as t-shirt works better for rubbing the crud off of the aluminum.
Simichrome polish works well, I purchase at an auto parts store, like real auto parts store NAPA not the we have common parts chain but you can get it on Amazon too. https://www.amazon.com/Nunn-Finer-Si.../dp/B00BSJYQ9S
Leaves silicon/wax behind to seal the metal. Have also used Nevr-Dull to pre-polish before Simichrome. Available at home improvement big box stores or Amazon. https://www.amazon.com/Basch-Never-D.../dp/B0014IGAWO
I think one could do Nevr-Dull and use any wax as a follow up. I just like the Simichrome because I used to use it on motorcycles, held up well.
The one thing I have found is a problem is the aluminum polish generates a lot of black residue which will stain on an older fiberglass with dull (micro pitted) gel coat. Good coat of Zep or the other liquid floor wax used on old trailers applied first will help but I ended up working sections with blue masking tape to mask off the white hull from the aluminum being polished. Seemed easier than getting the stray black smudges off of the sides.
One last thought, the oxidation protects the metal underneath. It becomes a barrier between the metal and the air (oxygen) that would pit and eat the aluminum. If you scrub it off you need a wax/sealer of some sort or aluminum will simply rapidly oxidize until it creates that barrier to slow it down.