Strangely enough I tried your recommendation on the rear brake cable, and the cable clamp on the bottom of the cable doesn't bolt on - it's an interference fit. D'oh!
As you can see I added an inline lever for the front brake for her as she really wanted an additional lever on the tops and I don't like the original style suicide levers (because of the metal lever pressing directly on the cable.. puts a kink in the cable, which to me says bad idea) so I used a modern cyclocross style lever. This makes riding in traffic a bit easier for her (looking over her shoulder on the drops so she can reach the brake is a bit awkward) but it needs a stronger brake I think.
A couple of companies make long-reach double pivot calipers now so I'll look into them.
I do have a Dia-Compe 500 with quick release to go on the front soon to help take the front wheel off, but ultimately I want double pivot brakes on there anyway.