I'll second the idea of trying to get an F100 as a second body. When I did a wedding in similiar circumstances, I used an F5 for all the colour work, and an F2 for all the black & white. It was an outdoor wedding so I was able to switch cameras at will, and swap lenses between cameras. (I think I would have gotten confused if I used two identical bodies)
Whatever works for each photographer but when I used to shoot motorsports I always carried two Canon T90s. The idea was when the main body broke (never happened) I could switch to the backup without any hesitation or thought. After many events without any problems I ended up usually loading different films (or the same with different lens choices) in each and designating the different film type with colored tape.
Various Canons and Nikons. A Mamiya and a Bronica. A couple Brownies, and a Couple of Argus' (Argi?)