Hi Dave and Jackie welcome to the forum. I'm a Brit (Yorkshire) and the wife is a Canadian and we now live in BC but lived in Algarve Portugal for many years, we still have a house there in Monchique and we will be there in February and March 2013, so if you are in the Algarve at that time let me know and come for a BBQ, (you bring the beer)
The Algarve sees many folks escaping the European winter, favourite free camping is at Silves, Alvor, Sagres and Lagos, all very interesting locations, I guess you will know about these places from the UK forum you subscribe to.
I have only ever seen two fifth wheels in Spain/Portugal, one was at Jerez at the race track where F1 hold their winter practice, the other on its way to Sagres.
All the best with your new rig