Patrick, if you're taking the wheel in to get the tyre fitted why not just mark the rotation of the rim backwards. That way you don't have to find someone who'll fit it the reverse way round - if you get my drift. Save yourself an arguement, unless they're going to get righteous about it being a front wheel (but only if they notice that it's a rear tyre). Where do some of these twats get off telling you want you can and can't have mounted?
It's been a real blast following your (and Fred's) courageousness with this fix. Bloody well done!