was down in Portugal over xmas/new years in my ford transit and had no hassle whatsoever parking up and staying overnight! Best trip yet. plenty of smiles and good mornings from locals as i fell out the back scoffing porridge. my van doesn't look like a camper tho...
Its defo worth trying to park near somewhere with bogs and a tap though. Made life that little bit more comfy.
Avoid toll roads through france and spain too as the A-roads are just as good and you see more. fuel is cheaper on these too.
I googled the words for no parking and stuck em on my dashboard and surprisingly hardly saw any signs, even in popular places like Barritz! if you're in a town, just try park descreetly and considerately.
I will say bring all your driving/vehicle docs tho, cos the police do like to pull you over (or was it just me?) to then look at your front passenger confused when they realise theres no steering wheel on that side.
Totally rate Portugal as a place to visit regardless of surf. Pretty cheap. warm. nice locals. decent skateparks. Try see some Fado if you can. Siked for you man!