16 years ago... I went with a bonded in bronze strut for it's hydrodynamic efficiency. Since then we live in fear of snagging a crab pot at speed! With our 5' + of exposed shaft, it would probably ruin the strut & $1,000 shaft!
If it ever comes to that, I would build a "V" shaped strut that I can make of carbon fiber.
In your case, that makes sense as well, but you have access and abilities with SS. I would use 316 SS, try to match the welding rods, and bond it to the shaft with an interior
wire to a shaft brush. This way your shaft zinc will protect the strut as well.
You never know until you try it, but you may have success with a rough sand, etch / prime process, and painting the strut with bottom paint
Our bronze strut is galvaniclly protected like described above, and we bottom paint