Is 20mm of spacers above the stem safe temporarily?

I'm trying reducing my handlebar height (Revolt Advanced 2). I'm down 10mm so far and would like to go another 10mm. Is it safe to do a few rides with 20mm spacers above the stem so I can decide if this is the right height before getting the steerer cut?

In particular, I'm worried about the stem's clamp bolts being below the expander, putting pressure on a section of the steerer that isn't reinforced by the expander.