The tow ratings are there for good reason. Read one of my latest posts regarding this:
zer...72903
There are no 'guidelines' that determine how the tow rating is calculated. It's different for every mfg. It's based on vehicle design, braking capacity, engine power, cooling capacity, etc. Exceeding them can result in loss of control, damage to the vehicle, and likely void your vehicle warranty. In some jurisdictions, if you exceed the GCWR (total weight of the vehicle, passengers, cargo, and trailer), you can be charged/fined.
I have driven my Rogue loaded to it's limit of 1000lbs. While it seems it could take more, I would never push it. If I need to tow heavy stuff, I borrow a friends truck instead.
Some may ask why Nissan imposes such a low tow limit? Most if not all Nissan passenger cars have a 1000 or 1500lb limit. Only the trucks/suv's go higher. Whether this is deliberate and if there is some 'safety margin' built in, we will never know.
I have added links to the towing guides in the FAQ. Here they are for reference:
2008 Nissan Towing Guide
2009 Nissan Towing Guide