I built a snuffer for my SC20, and am working on a larger version of the same design for Flight Risk (a custom 24' cat w/ a large assym spin). I've been constructing a hoop out of 1" dia. alum tubing (will use 1.25" for the bigger boat), welding a bracket to the hoop at about 45 degrees, the bracket conforms to the outside dia of the pole, and is hose clamped to the pole. A nylon sock is sewn (Sailrite offered advice on the appropriate fabric) with a few "belts" of webbing around the outside of the sock to provide attachment points, and attached to the outside of the alum hoop with glue and s.s. self tapping screws (with special washers). The hoop attaches just forward of the forestay bridle, and the sock extends aft alongside the pole, then under the tramp.
Don't see why this wouldn't work for you application. Sock length would be related to the number and placement of the snuffer patches on your spinnaker. You might experiment with hoop diameters before final construction to find a size that the chute passes thru easily (I'm looking at 16' to 18" diameter for Flight Risk). PM me if you want pics.

Dave 509 276 6355