You could do what I did and get the Barney cage and the 12" silent runner
It fits really well to the bars and you have loads of substrate underneath! Only problem is it's not a cheap wheel - works out at about £30 with the cage mounting plates as well. £25 on its own - and there's postage on top.
It kind of hurt getting a new wheel to go in the cage when I had a perfectly good wobust wheel, but it fits so much better.