Hello,
I also breed and show modern game and old English game bantams. I personally coop my birds in the 4-Hole exhibitions pens that are most commonly used at shows. They are very handy to coop each show bird individually to prepare for upcoming shows, are portable, and easy to dismantle if necessary. They are also great to use as drop pens in the yard if you don’t want specific birds running loose (I put my show birds out in these so they can get grass and fresh air without getting dirty.) I currently have two of these pens, and during show season I have them stacked on top of each other with plywood attached to the bottom of each, as seen at shows with double stacked pens. I have other cooping, so only my show birds are put into the exhibition pens. I cannot remember the company/brand where I purchased these pens off the top of my head, I will have to check when I get home.
I also know of many seasoned exhibitors who prepare and coop their show birds in this method.
Hope this helps, and good luck!