Think about your options first and do the actual cutting/Drilling AFTER you Are Sure that is how you want it. Also, Make sure that the truss rod nut is
put in the slot correctly. It looks like the nut is on top as opposed to the bottom where I think It Belongs. You may wanna check with the directions on the website or ask someone here that's used to installing HotRod Truss rods. I think you'd be happier with a nice hole drilled thru the wood instead of slotting to the headstock. Again, That's just personal opinion, And you know what those are like. Also, The headstock has a curve to it and that would be hard to fasten a cover to, since pickguard plastic is fairly thick, it would resist curving how you want it to be.