Chances are that if it pulls really bad, the hitch is adjusted to tight. If you had a 1960's station wagon, then you must put weight on the front axle, and that is when the WD systems where developed, for CARS! A truck, especially a F-250 or F-350 that can handle the 1,000 pound hitch weight uses a WD system, it does not need to be very tight at all. The front axle starts out with well over 3,500 pounds on it, and is likely to not pop up in the air (like a CAR). The rear axle only has about 3,000 pounds on it, and the ride will benefit from the extra weight.
Try this. Hitch up the ball only. Attach the bars by HAND, with no extension bar. (it will be to loose and very loose at this point and not distribute any weight). Check the links in the chain, and count them. Then tighten it only 1 link. Does that put a 'little' pressure on the bars? (little is not a exact science term, so you probably need to tighten it one more link.) But do not go wild and try to get the front bumper to curtsy, and drop by 1/2" or anything. That is something that a CAR would do.
Try it out towing, without the ATV's. Lets estimate your hitch weight at say 800 pounds. The wheelbase will determine how much lighter the hitch weight will become ONCE the 800 pounds of ATV's are put into the trailer. If it tows fine with the WD loose, and no ATV's (we will get to that later) then try it with the ATV's. However the ATV's will drop the hitch weight, so it will need to loosen the WD system a little bit to make up for the lighter hitch.
How much lighter? That really depends on the distance from the center of the ATV weight to the rear most axle, and how much distance it is from the center of the axles to the hitch ball.
For an example, lets take a im-perfect trailer. Lets say that the trailer ball to center of axle is 10 feet, and it is 10 more feet to the rear door, and your ATV is hanging 1/2 way out the door, so it's 800 pounds of weight is at the door. If the hitch weight was 800 pounds, you have just counterbalanced 800 pounds off the bumper, and now there is 0 pounds on the hitch. See where I am going?
For a more realistic measurement, your trailer might have 26' overall length, so 18 feet between ball and center of the axles, and 8' center of axles to the rear door, with the 800 pound ATV load about 4' forward of the rear doors (center of load weight). Or 18' from ball to center of axle, and 4' from axle to center of 800 pound load. 18/4= about 4.5:1 So for every 450 pounds of ATV load, you will take away 100 pounds of hitch weight (IF YOUR distances are the same as this example).
You have no clue if your hitch weight right now is 500 or 900 pounds. It is probably somewhere in between. It MUST never be negative weight. So once the ATV is loaded, you should have something heavy in the front of the axles too, like clothing, food, ect. Perhaps the water tank is forward? Normally they are. So will the grey and black tanks, so you should have 'plenty' of hitch weight.
Have a great time camping!
Hopefully the trailer will behave with the WD bars much looser. Then try it with the ATV inside. With such a light trailer, towing without WD bars would be acceptable, (for a 2500 series truck) except that your hitch (and all brands of hitches) require the WD bars to be rated at 10,000 pounds GTW and 1,000 pounds (or more) hitch weight. Most hitches are only rated at around 5,000 pounds GTW and 500 pounds hitch weight when not using a WD bar system. Only a few are rated higher weights without the WD bars.
Fred.
