Just to help educate you as there is plenty of misunderstanding out there w/ regards to towing and capacity...
4000# gross towing capacity is the old * as in
*properly equipped blah blah blah. The blah blah blah is important and means...
Total weight of cargo + passengers + accessories + actual item being towed must not exceed 4000#... all while assuming tow vehicle has proper running gear: correct weight class hitch, trans cooler (if needed, etc.).
So, lets assume you have proper class III hitch for towing. You also have:
450# - 3 total occupants (driver + 2 pass) and on average each is 150#
500# - 'Accessories' (3rd row seats, sunroof, Nav, 2nd row A/C, DVD players, etc.)
150# - luggage/bags/stuff for occupants in the vehicle.
1100# - total cargo
Total above, 1100#, gets deducted from total gross towing capacity to find out MAX trailer weight left available. In this case it would be 2900# (4000#-1100#). With an aerodynamic load, a boat for instance, you can "cheat" a little more...
That said, the bigger issue usually isn't get up and go but rather stopping. Brakes/rotors/pads on many domestic vehicles, sans those designed for towing like F250/350s, are undersized and pretty well maxed out w/ just occupants, accessories, and interior cargo. Add in a trailer getting close to total max will overheat your brakes the first time you tow and rotors will glaze and/or warp quickly.
Also, FWIW, recommended tongue weight is usually just 10% of trailer weight for proper load distribution b/w tow vehicle and trailer... so 290# in this case (but could go up to 400# 'properly equipped'.
To play it safe, assume towing is like electrical circuits in a home... aim to not exceed 75% max capacity of weakest component (which should be the breaker not wiring).
Good luck
