Are taller carbon fork expander plugs available? I recently cut my carbon fork steerer and it is a few mms too short for my desired spacer arrangement. If it was a little bit higher, then I could move a spacer from above the stem to below the stem. 

My expander plug sits 1mm above the top of the steerer column. It occurred to me that if it were a few mms higher then I would be able to add another spacer. 

Are there slightly taller expanders available?
The critical thing here is how much steerer tube length the stem is clamping. The expander plug does not add any structural strength and the cap must be of slightly less diameter than the steerer otherwise it would prevent the stem clamping it. 

If the stem overhangs the end of the steerer tub by more than a few mm, then the stem is mounted to high and could possible stress the steerer tube too much.

If you need to raise the bar consider flipping the stem so it’s angled up rather than down.