Thanks to all who helped. Came back from the trip. Even though the JFK-LIS flgiht was on time and landed at 8.15, it would've been unlikely we'd make LIS-OPO flight as the bags took a while to come out. And the drive from LIS to Douro valley clocked in at just about 3 hrs, 99% of it on an empty highway, so time savings would have been minimal if any.
Two tips - car rental at LIS would have been $150 higher than at Oriente station 6 euro cab ride away...and LIS-AGP car rental would have been 500 euros higher than 2 separate bookings LIS-Elvas, Badajoz-AGP, which are separated by 20 minute 20 euro cab ride.