1/4-20 J-bolts with large diameter fender washers and wing nuts, hook the "J" on the rack with the bolt passing upward through the bottom of the crate. Drop a fender washer over the bolt from the top, install and tighten wing nut. After the initial installation all you have to do is loosen the wing nut enough to disengage the "J" and pull the bolts out from the top for storage. A small handlebar bag or seat bag attached to the crate would work great for storing the bolts between trips.