The Kimpex box fits nicely and has minimal rear hangover (about an inch). The side leave about 1"-2" of tubing showing. I liked that due to the fact I could still use the rack for other purposes. I permanently mounted mine with u-bolts prior to checking out seat removal. The seat does not come off as easily as it once did, but since I don't remove my seat that often, its not a problem. To remove the seat, I unlatch it as normal, raise the rear slightly, and then pull the front back releasing the front "seat ears" (for lack of a better name). To put the seat back on, just reverse the procedure. I'd be happy to send you a photo tomorrow if you'd like. Hope this helps!!