Yep. Have a flash meter.
Main light will have a 21" beauty dish (which from experience seems pretty "efficient"). Secondary will be a reflective umbrella.
I like the idea of the reflector. My only concern is throwing so much light on the subject's face that they squint. The scene we have selected will have the camera facing pretty much exactly Northeast, so no matter what, the sun won't be directly behind the subject. I'd like to take this in the early morning for the light, but we usually don't get good clouds around here until the evening, so odds are that's when we'll shoot.
The more I think about this, I think I'm thinking too much about this. What I need to do is get out and shoot the damned shot.
Thanks for your thoughts!