You don't need a pickguard to be able to switch pickups. Everything would just be routed on the backside, and the slot for your switch, and holes for your knobs. Then if you decide you want a pickguard, you put it on. Now if you do this, then you will have your screw holes in the body, and most likely not go back to one without a guard, but it at least give you the option in the beginning. If you front route it - you have no choice - you need a guard!
Maybe I am not understanding your comment?