Safe steerer spacers stack height
A total spacer height of 30mm below and 5mm above is quite typical, and certainly nothing to be worried about.  The most important thing, since you have a carbon steer tube, is to make sure you use the proper compression plug and the specified amount of torque when assembling it.  Also make sure the top of your top spacer is just slightly higher than the top of the steer tube, because the top cap needs to rest on the spacer (or stem), not the tube.

Don't forget you can achieve some bar height adjustment by flipping the stem, too.