Just an idea...
You might be find insightful to look at the bond allocation percentages used by the target retirement funds that assume people will retire in 10-15 years.
Not that you'd want to do the exact same thing... but it'd probably give you a little clarity.
FWIW, and as I've shared before, I would not assume you have the stomach for a bondless portfolio unless you've already been through a bear market and felt fine with no bonds.