You may find some places do not allow motorhomes to park in, front line from the beach, car parks even though there are no signs. We found this at Torrenostra last winter. We received a local police notice, not a ticket, and parked in a roadside bay overlooking the empty car park the next night without problem. We were told by a Guardia officer last winter that, using opening out windows and/or deploying a satellite dish, also are considered as camping not parking. Roadside parking isn't a problem in urban areas, but camping is, however if there are parking bay marking you are expected to use only one and not park across bays.
There are now a number of Camperstops/Aires where it is possible to drop in and get water empty your toilet and waste water for a small fee. There are also public water taps and natural springs (fuente). If the locals are collecting water then we also use that water.
Avoid parking with the crowd and you should be OK. Hoards of vans packed in tight attracts the attention of the local, and the Police. We do not park during the day at the place we intend to spend the night and do not use the same spot overnight on more than 2 consecutive nights. Keep moving slowly and play the game.
The Mediterranean cools down to below 15c by mid December and it is then as cold as the North Sea in summer. That said it is still possible to sunbathe even in the coldest UK months. The nights are longer than in the UK and can get down to freezing even on the beaches. There was snow on the beach at Valencia last winter. During the day it was great standing on the beach in shorts and T-Shirt looking at the snow capped mountains just inland.
Legally it is not permitted to occupy a parked motorhome other than on a campsite in most of Spain, but many authorities take a relaxed attitude. They expect you to use campsites (many are closed over the winter) to support the campsite owners.
