I actually have had a chaff cart that I had built in the nineties and stopped using it a couple of years ago. Unfortunately I scorched my neighbour burning the heaps, not seriously but it was quite the effort to burn all those heaps every year. Right now we just let the weeds out compete each other. I have made a device to spray the trams. I may use it more next year.
The chaff cart was effective in keeping a clean system clean . I stopped using it for five years or so and paid the price.
I have racked me brain how to make a weed distructor. I have considered a rod mill trailed behind the harvester (like a ball mill but with poly rods inside) I have considered separating the fines and coarse seeds and using a flour mill for fines and a roller mill for coarse. This system at the moment has a sieve behind the grain pan to limit the material that goes into the stream. Apparently the new Harrington system is much less entailed that the DeBruin machine, it is also mounted directly on the harvester.