If the anchor had a bouy with a short tether from the buoy to the boat, you could just disconnect the boat when ready to head out, and leave the anchor at the beach. I think that attaching to the main crossbeam below the mast will work for you, if it wanders too much, consider a bridle that attaches to the main crossbeam outboard near the hulls, with the apex near the bows. The bridle could be pulled back on board or bungied to one of the forestay tangs. I'd shy away from attaching the birdle to the forestay tangs on an A cat.

Dave

Boyer A
F18HT