How does the bar diameter compare to your receiver. Maybe all a 2nd-hand bar would need would be cutting it to length and drilling it for a linch-pin. The advantage is the location at the end of a lever arm. I like the range of adjustment 5 or 10 pounds or hundreds.
Moving weight to the middle allows the car to spin easier, heavy weight out at the bumpers tends to keep it on course and also ride nicer. I have two five-gallon cans under the hood and I keep the right one full to improve the left-right balance.
Beyond the springs (literally
) you have tire pressures and the contact patch. These can be biased to control the handling. Dune buggies are a good example of the extreme. Small hard tires on the light-weight front vs big low-pressure tires on the heavy rear end. Balance that!