Since it's supposed to be a sturdier alternative, I got a B-series LitePro clamp, and noticed that the part where the derailleur is attached sits further out than a K-series: At rest, ie. on the smaller chainring, a LitePro two-speed derailleur sits above the outer chairing.

Can someone confirm? And in that case, what two-speed derailleur would work with a B-series clamp on a Brompton?