Stern Anchor Choice

[felizcortez]

I'm trying to decide on a stern anchor for the boat. I have a 1980 Tartan 37 and currently have a 20kg (45lbs) Rocna as my main anchor on the bow. I've been looking at the Fortress FX-16 or FX-23 as a potential for the stern anchor but don't know which one would be a good fit. We are planning on cruising in the Sea of Cortez and are looking for recommendations.

Thanks.