Thank you for your thoughts, whitepine! I'm sure either would work, but I don't have any idea which I would like better in the context of the whole quilt. I guess this is part of the challenge of an MQ! I'm thinking I will mock up a bunch with just the white, and a bunch with varied, and see which seems nicer when viewed near the part 1 units.
On the technical side, it appears I will have to use method #3, as my computer does not print PDF templates the right size, even though it is set to 'no scaling'. From a close look at the photos, it appears there would be no way to accurately position the ruler without the template taped to it. Maybe I could draw the template myself, since Bonnie has given the measurements for the lengths of the sides?