Can I put in plastic sheets instead of wooden boards?

I have just purchased a 1979 caravan which had £3000 spent on it 18months ago. As we were spring cleaning it we came across a lot of damp on the front end. We stripped it all down. Now I want to replace the wooden wall sheets with plastic sheets and also put a couple of vents at the bottom as to allow air to circulate in between the outer and inner wall of the caravan walls to reduce the risk of further damp.. Is this a good idea
Many thanks
Blaine