There must be clearance for the box lid to open! The rack is pointing in the opposite direction that it was intended to do on a car. This adds some tongue weight with 2 bikes, but relocating the spare tire, and a few other small changes an acceptable tongue weight was maintained. The piece of 2x2 that was meant to plug into the receiver is discarded.
Another modification seen in the photo, is the tongue jack with the larger pneumatic tire. (good deal on sale at Princess Auto) Some of the very tight spaces that these trailers will fit into, are impossible to reach when connected to the car. On hard surfaces the small steel wheel provided, works great, but on softer and irregular surfaces, not so great. This was a big improvement for about $50.
From the photo that was recently posted using a "Sportrack" it would seem that a similar method could be used for mounting it. Cutting the arms shorter for just 2 bikes would help. Those hitch extensions lower the tongue weight capacity for tow vehicles and increase tongue rattles that are annoying.
Re annoying hitch rattle. The attached photo of the U Bolt device sells for about $18 at Princess Auto, and a much better version for about $45 at Cdn Tire. Either one gives you great Bang for your Buck! So much nicer trailering without the rattle. Adjusting the bolt under your coupler will help also. You should have minimum clearance, without binds, throughout the normal movement while trailering.