Customers might object to paying the full price for a vehicle where components and features are still missing. Additionally, there are some components that are very difficult to install after the vehicle has been built. Not impossible, but requiring a lot of man-hours to do it, while being rather easy to install while the vehicle is being built.^ That would be the right way to handle it. Put everything in that you can and retro fit the missing parts later. My guess is that task is probably beyond what most dealers can handle these days as It would require personalized instructions etc.