Doesn't have to be a porteur rack but that would be certainly the way I would go. The most cost effective solution is any front rack that is strong enough to hold the crate will do. For that matter many rear racks would also fit on the front. Look on CL or the local buy and sell and pick an inexpensive rack. If the crate is too high cut it along the top. File the edges smooth and you have what you are looking for.