What kind of steerer tube? How many cm of spacers are you running already? I would check out your proposed setup with the Fork manufacturer, and the manufacturer of the riser.
And I'd be very leary if the steerer is CF. (other than the Alpha Q tandem fork that is designed for a lot of risers.)
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You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.