Why do I let myself get dragged into these things....?
There's a reason why tractor pullers see the front ends reach for the sky. They PURPOSELY position the drawbar as high as rules will allow with the INTENT of creating weight transfer that will cause the front end to "un-weight", shifting as much weight as possible to the rear wheels. With a "stock" drawbar position, at the very WORST, the front wheels would most likely only lift a very few inches, if at all.
Parts and pieces (like the ring and pinion) are designed to pull in one direction under heavy loading. And that ISN'T in reverse. Tractor tire tread is designed to pull primarily in one direction. Again, NOT in reverse.
Now, take your typical 2wd tractor and hook something heavy to the front end and start backing up. Weight transfers and you get instant wheel spin as the REAR END unloads. Go with a 4wd, and hooked to the front and you get the very same inclination to flip over, only FORWARD instead of backwards. Now I'm a little slow on the uptake sometimes, but why would a frontward endo be any better than a backwards endo?
In MOST cases I know of, the primary reason why a tractor would flip backwards is because of poor judgement on the operators part. Poor judgement when attempting to pull/move something far beyond the tractors capabilities. Poor judgement has no forward or reverse. Poor judgement is sort of a permenant neutral.....You ain't goin' anywhere.
My #1 rule for ANY operator, new or experienced, shift brain into proper gear before inserting ignition key.