There is a lot more engineering in a drawbar than many people believe.
This is a safety issue since the tractor can overturn in a heartbeat if a hard pull is hooked up incorrectly. Just getting it "below the axle" is no guarantee of safety no matter what anyone tells you.
The only drawbar I would ever use is a factory drawbar designed for the exact make and model of tractor it is used on. If a factory drawbar were available, a homemade exact copy might be acceptable, but the properties of the steel involved would always be a question.