if you could drive over the gate completely, enough to reverse dig or reposition yourself without hitting the gate, your front tire would have exited the gate. reversing at that point would be re-entering the gate in the wrong direction before the gate has been progressed.
But on the other side I have seen guy trying to clear a gate come to close with the rear tires back all the way out and do it again so would that be the same thing? And be called entering the gate backwards!
I guess there is nothing really in the rules to define "entering a gate".
IMO, like Jake said above, I would consider a gate entered once the plane is crossed or the front of a gate is touched. I would also consider that gate "entered" and you could come at any other way after that.
If you do straddle, take a reverse to correct yourself and go through the gate in reverse and call that "entering a gate in the wrong direction", you would also need to call this penalty for anybody who:
Drives both front tires cleanly through a gate, cant get their rears up and need to reverse to take a different line.
Drives both front tires cleanly through a gate, keeps the tires spinning in the forward direction and slides back though a gate.
Drives both tires to the exit plane, hits a ledge with their front tires barely exiting the plane and falling back onto the plane or simply having their tire bounce could cause them to bounce back into the plane after barely getting past the plane.
IMO, too many instances where you could accidentally cross the plane with the rear of the front tires and then come back in.
i can see an instance if we leave this unchecked that a guy could drive complely over a gate marker( front and rear tires both passing the gate)
If you straddle and get 1 front and 1 rear through, thats considered progress/gate. No correcting the situation after progress has been deemed.
Edit:
Maybe you meant that the front straddles and the rear does not straddle and then you back up? IMO, thats in the rules and possible. I think as discussed, the way to avoid this would be a taller gate.
I was thinking of some simple tall gates. I think you could drill a hole in the middle of a gate and then just put a 3" tall wooden dowel in it? Then you cant straddle without hitting it. If you had all your gates with holes in them, you could also put different length dowels in there to make them different heights.