I fly an asym tacked to the anchor roller all the time. Trust me, at some point you will fly it in more than 12 kts. I run the tack line from the cockpit through a block with swivel shackle hooked to a heavy line tied tightly around the anchor roller itself (the rubber roller part) This allows me to get the tack much lower than using the bale and it keeps the load off the bale.
But Fair winds, Mike C380 #77, Debbia Racine, WImore importantly I suggest adding a Bobstay. As is, the anchor roller is designed to accept down force, without a bobstay, the upward load from the asym tack will eventually work the anchor roller loose from the deck and cause leaks. In extreme cases it can bend it or even rip it out. You’ll be surprised at how much load there is on the tack