Have you looked at a buggypod? Zarava Flutterby had one when we went to the zoo and it looked great - I know she got it on sale really cheaply too. I'm not sure how it would work with a Bugaboo though?
I've never seen or heard of them! Thanks hun, I just googled. Clever design, but I'm not sure how practical it would be for every day, getting up and down gutters, over tram tracks, rough ground etc? I might have to PM ZF and ask her how she finds it.