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What kind of loads are on the piece of steerer between the two headset bearings anyway?
Significant. If you hit a bump, or brake, and the front wheel tries to go forwards then the fork legs will try to bend backwards. The steerer is constrained by the upper and lower headset bearings, but there will be quite a lot of load on the bit in the middle, which is essentially what's stopping the fork legs from disappearing under your bottom bracket. Headset bearings are only skinny wee things and won't resolve those sorts of forces.
Just drill it and then reinforce it with your recently learned carbon expertise. A slightly more cultured version of @jdmitch ‘s bolt that sucker right on.
What kind of loads are on the piece of steerer between the two headset bearings anyway?