There is nothing wrong with an aluminum trailer as long it is designed properly and the right materials are used. Most tanker trailers have aluminum frames.
The aluminum alloy to use is 6061-T6 extrusions, not 2024 or 7075. To weld 6061-T6 you need a 5356 filler and 6061 will recover after welding. High end aluminum trailer frames built from 6061 aluminum are joined together just like an aircraft frame with Huckbolt fasteners and there is minimal welding.
By the way, Huckbolt fasteners are as strong as welding.
https://applifast.com/wp-content/upl...vs-Welding.pdf