GU steering alignment

I'd be getting it checked asap, it sounds like you've bent something to put the steering that much out.
I know when I've hit something in the old troopy hard enough to break a centre bolt the wheel only moved about 30 degrees.
I don't know that I'd be game to drive yours too far in that condition.

You have bent something for sure. But it really does not take that much to offset the wheel by 180 (better hope it hasn't gone round a few times). Unfortunately there is no adjustment to correct this on the GU Patrol. The drag link is fixed and the only adjustment available is the toe-in, which won't fix your problem. Go back to where you hit that stump and try doing the other side ;-).
Cheers

For the wheel to be out by 180 deg suggests the pitman arm spline has spun.

Can't visualise a bent tie rod on one side causing this much change, and if it could, the toe in/out on that wheel would meana the tyre would be scrubbed out in a few ks.

Are you sure it's 180 degrees - that's half a turn...