Backrests are nice, and those are cool because they're really set back, there's nothing to get in the way of your arms, like an angled A frame. I'd totally leave them, put your time and effort into reupholstering them instead.
Yeah, like everyone has said, I'd leave them as well. I would just remove the cushions, reupholster them, and paint the frame with a color that goes with them and your cab. I could see white being a good choice for the frames.