Back in my circle track racing days, we used a home-built set of suspension scales made from square steel tubing. Each wheel was placed on a fixture 3 feet long that rested on a bathroom scale. 100 pounds on the scale was the equivalent of 300 lbs. at the wheel. We would adjust spring rates and jack bolts to get the desired wheel loading at each corner of the car. We spent maybe $500.00 on the whole setup, including purchasing the scales, instead of several thousand for a set of electronic scales.
Jerry