Single sided spool holder Heavy Duty

The finalisation stages of my Lack enclosure required a suitable deck mounted spool holder. I wanted it fixed down to prevent it sliding off when the cover was removed or fitted. I also wanted something that was quick and easy to operate so decided on a single sided mount with a quick thread nut and bolt which is fairly typical.
The holder itself is probably hopelessly over-engineered but I figured I'm only going to make one or two of these and want it to last without snapping or bending. It