Is the board heartwood, sapwood, or a combination?
How you go about backing it will depend on that.
If it were me, I might just rip it and glue it for 3/4" thickness, then proceed with a nice pyramidal design, non-working handle glued on.
With 8" of width to play with, you could get 2 bows out of that board this way.
I would suggest if going that route, to glue up the rips 180 degrees. Rip it, flip it, glue it...
just a thought.
Mike