Many aluminum products have a finish that protects it from oxidizing and keeps it "shiny". This may be one of several types of coatings  or anodizing. If you sand the area, this coating will be removed and the aluminum will later dull.

A way to somewhat remove dings or scrapes is called burnishing. This involves the usage of a hardened steel instrument, rubbed against the aluminum while being lubricated by a light oil. The round shaft of a screwdriver and a light oil such as LPS, WD 40 etc will work.

Spray some oil on the area you want to smooth, and then by applying a firm pressure to both ends of the screwdriver, push and rub the shaft back and forth over the affected areas. The steel, being harder than the aluminum, will smooth out the high spots, and actually push the softer metal into the low spots.

You will not end up with a polished, smooth surface. But it will look better than when you started, won't later discolour, and won't remove the finish from around the surrounding areas.

Gard

That makes your trailer.... "Unique". Gives it "Character". Now, there's no one else on the planet with a trailer, just like yours!! At least its aluminum. Had it been steel, you'd be having rust streaks, running down the side if your trailer in a couple months.

LOL yep..that is a good way to look at it..  You know how it is, when ya have something kind of new you cringe when it gets a ding or scratch (or at least I do). :-)  I am the same way with saddles, vehicles ect..  After I get a few marks I won't fret so much.. just like to take care of stuff and keep it looking nice. I agree on the steel and rust, been there and done that.

I think my mare was jealous yesterday.. we had her tied to the side of the trailer facing the arena and we were trying out a new gelding. She is not a trailer chewer.. so I think she did it on purpose.. LOL, she was giving me "that look".