Sounds good. It's really too bad they don't rent Technikas, though. For what you are doing, it would be ideal. You don't need any of the extra bulk of a monorail camera, and being able to lock right into infinity focus mechanically instead of visually would simplify your life and make user error less likely.
Just remember that a 75mm lens is the widest you can go on 4x5 without going wider than your 21mm lens on 35mm film. Even the 75mm will "seem" a bit wider because 4x5 format gives you a fatter frame.