I still think you would be OK, we could actually turn back on 6-40's if you tapped the brake, but I didn't have fenders either.  Yea, I know we got the fronts wide..  Sorry but I don't have an operators manual anymore. 

FYI, the new 315 with front duals has the stops set so the fronts barely turn and it still will get back on 8-40's. 

On most fields we don't have headlands, just a drainage ditch so on my point rows I have to backup.

Edited to add,,,,, I just thought about it,,,,, you are probably pulling your implement, we have mostly 3 point mounted stuff, so tapping the brake and pulling around the front is a lot easier.