I have never seen an aluminum dump trailer, and when I looked into buying mine I looked at over 50 manufacturers...there are tons of manufacturers out there, they might not advertise, but maybe they can build you one...not sure how much weight you would save vs durability...eventually you'll run into, dent it, ding it anyway so paint inside the trailer should be an issue. In NYS you can have a GCWR of 26,000 w/o CLD. I have a 12K 6.5 x 12 Cornpro Deckover that can take a machine with ramps that store under the bed. It gets a little hairy loading my subcompact backhoe into it with the angle, but I didn't want a low profile because they have a lot of clearance when the trailer dumps so they don't dump loads as well as a deck over. My trailer is heavy, almost 3500#, and the GVWR includes the trailer weight, so I should only have 8500# in it. It is a beast, real heavy duty! PJ and Cornpro I think are the only ones that make a deckover with ramps. Plus mine has a drop down side which is great for loading sheetrock, plywood, etc. and since my tractor doesn't have a lot of clearance under the front bucket it makes loading the trailer easier too...