The new edition of All the Aires Spain and Portugal has 76 entries for Portugal and 156 for Spain. There are also detailed listings for AutoGas filling stations in Spain and Portugal. It's not usually a problem refilling gas in Portugal but the Spanish listings will be useful to anyone with refillables or a bulk tank.
It's a few years since we spent any time in Spain but we didn't have any problem finding wild camping spots, specially away from the coast. Nevertheless I've got a copy of the new edition as we are probably off to Morocco next winter and will be spending a bit of time in Spain and Portugal on the way back in the spring. It's always useful to have a list of places where we can be sure of being able to park up for a night plus refill water and dump waste. The good thing about the Vicarious Books guide is the photos, so you can see what sort of a place you are going to.
There are a few discount codes for Vicarious Books around from time to time, this one: 'ukmoto' gives 5% off.
AndyC