Hmmm.. One thing I didn't consider here would be that if the empeg were in the dock AND the switch was set to ignition, it would be possible to have the amps on without the empeg itself actually on.

That might cause some thump issues with the empeg if it was turned on and off - I don't fully remember the problem there.

I'd still try it that way initially. Otherwise the switching could probably be made a little more elaborate to prevent it.