Here is where I am at with my 2nd try at this (this picture from about 15 minutes ago). It's just resting in place but will mount only about 1/4 inch higher.
Obviously not done. I haven't drilled the mounting holes or flamed the edges and of course it's covered with my hand prints and acrylic shavings but I'm getting there. I now know it clears the top so that's a relief.
Gotta take a break - may finish today, may not.