I build a collapsable motorbike trailer. The main section and axle was made out of folded galv steel in "tophat" shape and bolted together like a crucifix. Suspension was Towsure units. The plans was to make quick dissassembly but seeing it only took a few minutes to bolt things together never bothered.
Paul H
I'm sure some one on here had something similar
From this... View attachment 32424
To this... View attachment 32425