welded ?
Steel is more resilient and easier to weld than aluminium, if you have no need to max out the payload there is no advantage to an aluminium frame. How do the attach they aluminium body frame to the steel trailer frame ?
This applies especially when doing hybrid things...
" Stories abound about commercial "camping" trailers coming apart over time, particularly if taken off pavement "
My trailers have thousands of off highway miles on them with zero issues. But I've seen many cheaper ones fall apart.
I completely agree. We're not talking much weight difference between aluminum and steel and the flexibility of steel frame is a better solution for off road vibration.
Better to spend the money on the interior with lightweight aluminum profile (like 80/20) for shelving/storage/bed. This is where the weight starts to add up if you try to build everything internally with plywood.