I would love to have a rudder like the one you pictured. I have skinned my rudder that was damaged by Milton and as you can see it is mangled beyond repair.

Unless there is significant corrosion I can't see, it looks repairable to me. Can be done on a flat bench.

I would use chromoly. Rough straighten everything first so you can make a form, or trace the shape on the bench top.

Remove the trailing edge and discard. Straighten the ribs, using heat where nessesary (reinforce or prefabricate if too far gone). New trailing edge is made by filling the new tube with sand and cold forming it around the form you made.

I understand it's challenging if you have no metalworking/welding experience but anyone who works with TIG should be able to do it.
S