Removable inner forestay anchor point.

[duckpond49]

I had a sailboat with a removable inner forestay that was primarily used to help "bend" the mast. It had a backstay adjuster and the mast base had a
"rocker" design to facilitate the movement. Your rig looks designed to add a staysail jib. The inner stay attaches to the eye and the sail tack point to the "handrail".

[Mike Banks]

There is a proprietary fitting for this purpose which is pulled up so that the fore stay can be snapped on to it using a throw-over lever and I think a pelican hook. I would NEVER use one or anything like it mounted in the middle of a deck space on the centre-line of any vessel. I always rig a bridle and fasten to that. Safer and easier and stronger.

Fit two smaller ring bolts that are recessed in their mountings to your deck one each side of the bow, and snap a SS wire bridle into these--the bridle having a ring link in mounted in the centre in thimbles. That will stop you losing a toe in the usual ring bolt in the middle of the working area on the bow. It will also be a much stronger attachment.

My storm sails I rigged with extremely strong synthetic non-stretch bolt-ropes spliced into thimbles and then to these were fastened my snap shackles at the attachment points. Fasten the base points first, then attach the halyard, and tighten the sail bolt-rope. My storm sail is loose-footed, has a longer bridle, and sits much further aft from the bow than the attachment points for the extra jib.

Using the same system of pairs of ring bolts set on or close to the toe rails, you can rig any number of centrally mounted sails or jack-lines. Although grasping a handy ring bolt once stopped me going over the side in a severe gust, they are a potential disaster for feet if mounted in walkways..

Stepping over a bridle sounds hazardous enough--but it is not a problem really as they are only there when needed. The rest of the time the decks are clear of obstructions and potential hazards.