All good advice so far except for this bit.
When you pack a trailer, the object of the game is to evenly distribute the load within the trailer.
The further forward you move the centre of balance within the trailer the less weight you will have on the front wheels of the car, this is where your steering and the majority (around 80%) of your braking effort comes from.
Most tow bars have a load rating that refers to the amount of weight the car may pull; usually 1200- 1500kg, but they also have a ball rating; usually only around 100kg. This refers to the amount of load that can be applied directly downward on the tow ball.
A good indicator is, if you can still lift the drawbar of the trailer and the trailer doesn't want to tip back, you've got the balance pretty right. You don't want excessive weight on the towball, but you don't want the trailer trying to lever the back of the car off the ground.
I regularly tow my trailer with two GSX-R 1000's and a bunch of gear, total trailer weight around 900kg and I can easily lift the drawbar of the trailer off the towball by hand. The back of the car drops maybe an inch, if that. Doesn't affect the handling of the car at all, other than lengthen the stopping distance.
Hope this all makes sense, enjoy your trip. Cheers, Dale