Anything you may want to do won't be legal in any sort of way with a CRX back seat.

American Market CRX's didn't come with back seats, they are "2 seaters", even if you buy one from Japan it's not legal because the American models didn't have them.

Anyways, install it if you want, put your kid in their too, just don't come crying back here when your friends the cops impound your car, take away your license, and give your kid to a foster home.