It will, of course, have your signature inlaid gold ring and rivets...?

Even if you forego the ring, I don't see how you could possibly resist
a nice triangular arrangement of gold rivets. Probably need, what,
about 1" thick rod to keep them in scale?

Seriously, it might make sense to just forget machining the back and
save the bucks, other than drilling the mounting holes -- the
difference in weight isn't going to make all that much difference,
given you will need to fasten it to the framing in any case. And if
you get it water-jet cut, there won't be any distortion. I'm not sure
what is cheaper with that size stock, plasma or water-jet, but not
machining it might make up the difference in any case. Might not
distort even with a plasma cutter -- you see that fancy scroll-work CNC
cut stuff all the time, and it doesn't warp, although of course it's
much thinner than 1/2 inch stock.
..
Regards,

Bob