Well the trailer itself is made specific for towing 2 Atv’s. It’s a side load, meaning they drive up and down from the side. They JUST fit on, no room to adjust forward or backward load. The axle is placed to give it the 60/40 balance.
@HotWheelsBurban it is level, but maybe I’ll try giving it a bit lower tilt like you mentioned. Other than that, wheels are balanced and good on truck and trailer. Another thought is after reading something on E-trailer is if leaf springs are too stiff, that could cause a shake. IIRC, I don’t remember a shake before doing new leaf springs. But, it may have had a bit of a tilt like you mentioned.