Andrew, I know, the northwest has had a streak of high temperatures. At 80 to 90 in the shop and darkroom I've had to work in the evening and little at that. In camera separations in ULF would not be workable. A previous instructor who did dye transfer shot transparencies with an RB67 then made separations and matrices etc.. Digital negatives does solve may problems. Duotones sounds interesting, I'm thinking of Edward Steichens "Pond", adding one more color adds a completely new dimension to the monochrome look. I hope you keep exploring this avenue.