Hello Zee,
Don't think twice about bothering to put a spinnaker on an A-cat. Enjoy it like it comes, with one sail. You could be very happy with everything just that way, and fly like the wind! It's just the crazy adreniline-junky guys who have to push it (The Envelope) too far.
3 women and 36 men camre to sail A-cats at Islamorada in the Florida Keys in January: the women did NOT come even close to last, but did very well. Also, one of the local men that attended his first big regatta is small and 56 kilos, and he uses a righting stick (power pole) to right his Bim 2000 (75 kilos). He doesn't capsize much anymore.