Nope, both AEO and pilots have independent Garmin systems and, for the type of VFR navigation 558 requires, there is absolutely no need for a navigator on flights made in accordance with the restrictions of the Permit-to-Fly.
If a map-and-stopwatch back up is needed, the non-flying pilot can do that.
GPS will provide waypoint ETA with sufficient accuracy for an airshow display slot to be met - and you don't need to have had months of theory at Scargill International plus hours of backwards flying time in an ancient twin-jet to be able to operate a Garmin!
A 'Calc 2' was one of the electro-mechanical computers included in the V-bomber Navigation and Bombing System.