We purchased some aluminum extrusions shaped in the form of the ramp mounts then I needed to add the hinge rings where I wanted them You can buy these already welded in place but the ones we wanted were not in stock so just bought the pieces.
plus we wanted to add more strength tot eh mounts than what they would have been. So I welded a 1/2 by 3" flat bar tot eh rear of the trailer before welding on the extrusion then to further protect the rear of the trailer I added a strip of 1/4" by 8" flat bar welding it to the extrusion and to the trailer floor
First off I haven't done any aluminum mig welding since sometime in the 1990's and hardly any tig welding since then either. Most all of my aluminum welding has been done with stick electrode or oxyact torch.
Not too awful of a weld due to the metal being thick I preheated the areas before welding
You can never have too many clamps
Obviously not a perfect weld by any stretch of the imagination but it will hold