Hi RedYork
It seems you're up against it with only a week to go. hope you manage to source something asap.
Personally I wouldn't leave it to the last minute to fit racks; I'd want to give them a good test before undertaking a long trip. The last thing you want is a problem en-route and the luggage/boxes hanging off!
I've made a few trips to Southern Morocco with a cheap Rickman topbox on a rack and a small bag bungied onto the seat....more lightweight than racks.