I do not have an issue with my 200 lb hopper on the Hyfire II unless I use wet coal.
When I was burning it at the shop, I would buy 100 lb bags and usually keep them in my truck for added weight especially with this snowy weather. Then dragging the bags into the shop and direct to hopper would crate bridging.
However since I took it to the home garage, and since I keep a 55 gal barrel in the garage, I have not had any bridging in the past month or so. With the addition of the Coaltrol, and having it set to only 55* out there I don't use a lot. So when filling the barrel from the outdoor bin every 2 weeks or so, it has plenty of time to dry out before getting shoveled into the bin.
But being it is in the garage, I don't have any concern with dust mitigation.
ETA: How about using something like this suspended in the hopper and wired to operate when the stoker runs ??It's cheaper than a pocket rocket or rabbit !!!!! http://www.allegromedical.com//daily-li ... a_7c189870