I like the idea of proofing, and do it myself. Unfortunately I can't afford to have the electrical in my new darkroom installed for another couple of months (argh!) so I employ evil digital techniques in the meantime.
But to translate the pictures help a lot of the frames to find their way to me, and they would have otherwise gone un-noticed if I hadn't proofed.
Ian, perhaps you can consider different ways of proofing? It is after all just a proof to give you a rough idea of what's on the film, to see possibilities.
About pre-exposure proofing... If I had a DSLR I might employ it, and models are just as important to the creative flow as the photographers. Models know themselves best, and it is definitely a collaboration.
Coming back to work with the same model over and over again builds trust and a type of repertoire, so a second sitting is, in my opinion, almost required to get the best results. But that's just me.
Good luck, Ian. It's so nice to hear you're back in the darkroom!