Rate/Route shipment without carrier

We have created a blended billable rate for all of our shipments across all carriers. Is there a way to create one route (P4950) per origin per country(USA/CA) without entering a route for every carrier?

I tried putting a * into the carrier, but that's no bueno. My goal here is to have the shipment go through auto rate/route with no user selection required.

any help is appreciated.

thanks