After getting my motorhome I ended up with a right can of worms which you can see if you look at the other videos I've made on my channel as they have been resolved - its now fully functional and will last many years.
This rust issue is common on Ducato vans and as motorhomes tend to stand about a lot the water just rots them out but there are simple things you can do - none of the plastic panels you see are fixed - they just slot in and can be safely left in while driving the vehicle - they can be removed with a lift an pull...