Yes they could, pretty good couple of threads re. wings at SA in the Multihulls, with input from the C class guys who actually sound like they really know what they're talking about, including using wing with spin. They don't when class racing because of sail area restrictions btw...
I wouldn't say "spinnaker" ... more like a big code 0 or screacher. These boats will never have the apparent wind anywhere near 90 degrees.
Chances are you'll probably see a smaller jib/headsail when going upwind and the big screacher unwind for the downhill stuff.
