Driving time from northern Portugal to Carcassonne?

I am pondering driving from northern Portugal to Carcassonne. I do not know
northern Spain, nor the Pyrenees, nor the region south of Carcassonne. Am I
mad to consider the drive, since I have no time to tarry en route for
sightseeing, or is this doable? I had considered flying from Lisbon to
Barcelona, but the one-way fare is exorbitant. If driving is feasible,
please suggest the fastest route. Clearly, northern Spain warrants visiting,
but I have no time on this trip. I would appreciate an email reply as well
as a posting here. Many thanks.

Harlan
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