My idea has been to solder a block off plate on one of the exhaust ports and create a 3rd transfer port. Then solder a fitting to the other exhaust port that allows 1/4" ID silicone tubing to slip fit over it. From that point it would be a matter of trial and error [for me] to come up with a cannister that works.
A Pitts style that can tuck into the engine compartment behind the engine would work for me. Similar to the VA muffler.