Derailleur on a Raven?

[bokes]

I live in a medium theft risk area, so I'd be interested in installing and using a Sram dual drive (3 speed hub with 9 speed rear derailleur) on the Raven when at home, and switch to the Rohloff when going on tour.

I know I could always have a second commuter bike and put the Raven in storage between tours, but I'd rather not do that. Another alternative would be to mount a Nexus hub, but here in San Francisco I need a wider gear range.

Does a clip-on derailleur hanger exist that would fit the Raven? I'm aware this might void the warranty, but I might take the risk.
Thanks in advance.

[PH]

The hub is about half the value of the bike and only a few people realise their cost.  If you're worried about getting a bike nicked, get a cheap hack, the swapping hubs sounds like a lot of work, that's hub, front and rear mechs, wheel, chainset, chain, shifters and cables.  I carry a decent lock, have my bikes insured and save my worrying for more important things[]