Route from Bilbao to Ribamar

The shortest route from Bilbao to Alcossebre (for the Ribamar site) takes you off the motorway and on to the N232 at Zaragoza - staying on the motorway via Tarragona adds quite a bit to the journey.

But the N232 looks quite twisty with at least one steep gradient symbol south of Alcanz.  Can anyone vouch for whether it is ok for caravans?

Thanks.