Currently have a 1/2" subfloor, thinking about putting down aquabar on top of that, then 23/32" advantech, then another layer of aquabar, then the hardwoods.

Good idea or bad idea? looking for maximum moisture protection

It would be best to glue the advantech down to the existing floor, along with your choice if mechanical fasteners, nails or staples, to hold it until the glue dries. Then use aquabar. One layer should be enough.