We used pre-painted steel to clad our Teardrop. Known as Colorbond in Oz. We used a nibbler to cut it to size.
The steel is glued on the ply with aluminum checker plate on the bottom sections to protect the steel from stone damage.
The weight penalty was minimal.
We had little knowledge of Teardrops when we built the TD, had seen a few pictures which resulted in some chalk outline drawings on the back patio. In hindsight there would be a few things we would do differently.
Take it easy.
SD