Lol, my wife would harass me for getting Legos!! Every year we have a meeting in Orlando, basically stay at downtown Disney where a legoland store is. Gives me some away from home building to do!! Use to build them and give to nephews once home. But now they don't play with Legos so I've kept them for myself
.
I made some pieces of I-beam from 22 guage steel. Put a little camber in them, love to see trailers with camber in. For just tacking together they are stronger than I thought and light too. So I may go the steel build. Basically a steel skeleton with wood decking. Gonna try and make it able to handle 60#.
The pics don't show it well but from side it's rather a smooth curve.