Thanks, SVG opens a door to do this co-work with LibreCAD. I opened in Illustrator (so I can re-export to dxf) and it does not keep the scale. Maybe it's Illustrator that has a limit in size (don't know why) but it can be managed in this case, don't need precision, so I included a scale mark in the project to calculate it.

LibreCAD is slower with the same draw, interesting...