The thing is, you want to make things as simple and clear for clients as possible, especially on AW. AW is a busy and confusing site even if you aren't a horny so-and-so, so you can't really afford to risk increasing client confusion with multiple locations on different dates.
I think, therefore, that your idea of simply completely changing your location details on all bits of your profile depending on where you're *currently* working from is best. Sure, you'll still get the "I thought you were in Bristol/London/Lebanon/Peru?!?!" queries, but if you save a template email that says: "Hi, and thank you for your enquiry! I'll be in x place on abc dates and in y place on these other dates. Do call or email if you'd like to book. Thanks!" and fire that off in response to any non-booking-specific emails, that'll save you a lot of time and stress.
If you're mostly in London then all you have to do is write up and tell people your London availability, except when you're "touring" Bristol. It shouldn't be too difficult - I know more than one escort who successfully works from very different locations using their AW profile to advertise.