Does this seem a reasonable choice for stanchion bases?

[Manateeman]

Spartan marine makes some nice bronze bases that are really strong. I’m sure you can find other marine foundries. I’ve seen older designs which hold up a bulwark board as well as the stancheon. The bulwark board can have a space at the bottom to let out water, or be deck flush.
I think the ones I had cast had 5/16 or 3/8 bolts. The stancheons were solid tapered bronze , two lifelines...and a manatee could pull themselves over into the boat. Put em in with 5200...never leaked a drop in 30 years.
I have some of the stainless fittings in your photo. The drilled holes, I think, are smaller than 1/4”. Maybe just a size too small.
If you want to go stainless, any good TIG welder could set you up any design.
Happy trails to you.
The manatee crew.

[Kd9truck]

They make stanchion bases that do not mount on the freeboard, I would leave the freeboard alone and mount the stanchions on deck. The marine architects place them on the overlapping seam of where the deck meets the hull in almost every vessel that has stanchions. The toe rail is used to fortify this seem as well.
I gotta believe there’s a reason you don’t see them mounted on the freeboard portion of the hull. Just my 2 cents, cheers