hi Ian, sorry if this sounds a bit vague but it was a year ago and I didnt stay on site.
There is a camp-site near Arinsal, on the way up to Arinsal on the CG4 at a place called Erts, there is a roundabout sign-posted Xixerella to the left. as you exit the roundabout, look to your left and there was a site with carvans etc, dont know exactly how to access this area (presumably before the roundabout). Its a long way up so dont know if it will be any good to you. regards chris.