Looking great,I like it.
I free hand bent my pan out of an old heavy duty aluminum street sign.
Good thing is it is very strong and stiff,so I only need a rear underneath bracket to attach it to the frame(front to be held with battery strap or lip like a modern seat) as no other reinforcement is needed.
The bad is it's relatively heavy,so I may cut some holes in it and cover/seal the top of the pan with some rubber roofing sheeting I have to keep water/dirt/mud from getting to the underside of my seat foam.