I would advise that you go to your nearest Toyota dealer and get them to advise on the tow capacity of your car. They should also be able to show you the VIN plate on the car, which shows the maximum weight of the car fully loaded and the maximum weigth of the car plus trailer (Gross Train weight)
I tow a twenty foot twin axle van behind a Laguna estate (2Ltr). The van weighs a max 1360Kgs and the tow capacity of the Laguna is 1350 Kgs. The gross train weight is 2985Kgs. Having weighed the combination at our local farm supplies, I'm ok so long as I leave the equivilant of 6 bags of sugar at home (or 24 cans of Larger in the male rating scale).
As for being over the mythical 85% safe to tow limiy, it is a very stable unit to tow so long as there's 70-75Kgs of nose weight.
Oh just to add more confusion. My 70 year old father in law, tows a Bailey scorpio loire (17ft single axle) behind his Laguna 1.8 16 valve estate, again legally and without any trouble. But that is upto the max tow capacity of his car.
Sure we are both ex-lorry drivers, and between us have three quaters of a century of driving experience. But he only started touring 5 years ago. Experienced drivers may be, but we still learn more each day we drive.
A well loaded top weight van can be safer than a tail heavy loaded 3x4 foot camping trailer, even in the experienced hands.