Hello Jörgen
You could certainly use an extra stay to keep the bowsprit up.
You would need to have an arrangement which allows you to quickly slacken the bowsprit shrouds, to enable the bowsprit to be raised.
If you look at photos 5 and 6 in the album " Mary Ann modifications" you will see that I tension the bowsprit shrouds using a triple block system with the tensioning lines held in jamming cleats.
This enables me to easily release the bobstay and shroud tension, raise the bowsprit and then re-tension the shrouds and bobstay to hold the bowsprit firmly vertical. It only takes seconds to do.
I devised this system to help when raising and lowering the mast, but is obviously useful in other situations also.
Thank you for posting your photos, I am quite envious, I love woodworking/boatbuilding. Keep the pictures coming.