To The Bockerts:
Seems like a LOT of effort to solve (in my opinion, IMHO) a non-problem. What are you trying to accomplish? How many times do you think you'll have to choose between a fluke anchor and the Rocna? If the Rocna drags, methinks you've got the wrong size Rocna, too little scope, or attempting to anchor in an inappropriate place, or conditions don't warrant anchoring anyway.
Trying to rig two anchors for simultaneous use is an even bigger problem, as your existing windlass and chain locker setup isn't designed for that purpose.
IMHO, Your pulpit looks good in pictures, but just isn't practical to provide actual simultaneous (or even selective) choice of anchors. No chain stopper, no dual-gypsy windlass, no segmented anchor locker, no second hawsepipe, etc. And I'm not even addressing the pulpit strength required to deploy from that forward hole.
Again IMHO, should you REALLY need a secondary anchor, keep it in the lazarette, along with an appropriate chain rode and braited anchor line, ready for use when needed. Then, haul it out, deploy it by hand, and live with the incumbent difficulty of retrieving it when you're back underway. A second roller forward may ease that retrieval, but any additional work to house and/or deploy that second anchor from the bow seems like a solution to a non-existent problem.
Regards,
Pete