Make sure that the trailer ball is rated higher than the load that you will be pulling. Check to see if you are using the correct size ball. Check the bearings on the trailer. Inflate the trailer tires. Look for cracked, dry rotting tires. Check the lug nuts. Check your differential fluid. Use a hose from the fan side of the radiator to flush debris forward and out of the radiator fins (don't forget the A/C condensor and any other coolers). Inspect for fluids on the backing plates/drums/hoses/calipers. Check your wheel bearings. Check for play in the fan clutch/water pump and inspect the belt. I see that you are from Canada, check your truck and the trailer for rust especially around the frames, suspension mounting points, tongue, wheels and axle tubes. Periodically pull over and check the temp of your tranny cooler lines going into the radiator to see if you are running hot and use the back side of your hand on the trailers hubs to see if the bearings are running uneven temps or if they are hot. Use the manual control on the brakes PRIOR to going over a hill just to check that the trailer brakes are functioning. At the top of a hill do a simple brake check. I hate towing heavy (you are) without airbags to level the rear suspension out because the sag will effect your wheel alignment. A properly set up tow rig will stop decent but it will still take longer to stop so leave more space between you and the vehicle in front of you. All of that being said, GO SLOW! As I teach in all of my classes, "Be the witness, not the accident" and "If you are watching the tail lights of the vehicle ahead of you so that you know that you have to stop, you are following too close!". Not one of my sayings but it is a great one... Have you ever seen the term "GOAL" on the drivers mirror of a lot of the semi trucks? It stands for Get Out And Look. Safe travels!