If you use expression bindings, you can add this condition to display as desired when in Designer and not testing–a “design mode”:
// Show this if in designer and not testing.
(({[System]Client/System/SystemFlags} & 1) && !({[System]Client/System/SystemFlags} & 2))
// Also show under these conditions in client or testing in designer.
|| runtimeCondition
Replace runtimeCondition with the expression you’d want evaluated for the binding in a client.