>>1600068get something like pic related and zip tie a metal basket on it like a wald, and put a sheepskin rug inside it
What rack depends on what frame you have. I don't think a larger more expensive porteur style or full size front rack is strictly necessery for a 20kg load. But the very small front racks that mount on canti studs won't be good enough.
you can get cheaper versions of pic related and of wald baskets, from like any homeware/hardware store. Hell even a milk crate. Drill holes. Zip ties. Use big industrial zip ties. They're really strong.