You can leave it all on if you like - you`ll just have to add enough spacers above the steering stem to let you cap the tube and preload the bearings.

So I guess you really want to know what the maximum recommended stack height is below the steering stem. And that depends on the steering tube diameter and material - which you haven`t posted.

Recommendations vary from manufacturer to manufacturer and since you seem to want an accurate maximum permitted suggest to check the specs on the make and model of what you`re looking at or contact the manufacturer.

A full carbon fork with a carbon steering tube would have a shorter permissable stack height than carbon fork with an alloy steering tube if you haven`t already made a purchase.