The big cover is superb, but takes up a bit of space, and I wouldn't use it on a dirty car. So when touring, the cockpit cover makes more sense - less storage space and can be fitted over a dirty soft top! (I do have both and have used both).
But the Zetec/Duratec does get water in the plug wells, so you need some sort of weatherproofing. A plastic bin liner over the engine would do, but you would need an unmissable note on the steering wheel.
Adrian - my first cotton indoor cover for the BGT was made that way. Cotton curtain lining material pinned over the car and stitched my M.I.L who was an accomplished seamstress. I still have it, but not the BGT.
