Weighing for side to side weights

Used to own scales and weighed rv's by wheel position when I was a full time traveler. This question came up often, so I tried it with my rig at a scale where I could side step the platform scale.Very hard to find a scale with flat surfaces on both sides and no curbs/poles. Drove on with all the wheels on the scale segments and got that number for the truck and trailer hooked up. Was within 50 lbs of my scales I used to weigh each tire position. Backed up and side stepped the scale with only the driver side on the scale so I could weigh and get those numbers. Then drove off and side stepped so the passenger side was on and got those numbers. Guess what, they didn't add up correctly. The left side number and the right side number was well over 800 lbs more than the actual weight I got with the whole rig on the scale. Talking to a CAT scale repair man, he said the scales are platform scales and are designed to have a amount of weight across the platform of the scale. When only one side has weight it will read incorrectly. As it did in my test. He said why do you think we invest the costs of poles or curbs at our scales? to keep the dummys from driving off center and getting a wrong scale reading number. Makes sense.
Just for your info, my 2004 Mobile Suites 36 ft trailer was 1,100 lbs heavier on the driver side than the passenger side. And the front axle was carrying about 400lbs more than the back axle and the rig was level when moving down the highway.