The plastic moulding protecting the caravan frame has degraded and need something else to stop water damage between the outer aluminum shell and the wooden frame.... any advice or product suggestions welcome.....
Google ‘plastic channel’. Lots of options. I think that your biggest problem is bending it even with heat. Try phoning these places for advice.
John
PS. Even better if they have the right size. Might be black, but new vans have black. If the wall thickness is close to newer vans perhaps you may find some at parts suppliers.