Glad you got to get out and make some smoke today Cayu. I had fun with my daughters Impact as well. For your off hand shooting, try shortening your for-arm extension. Bring your hand back a bit towards the trigger and pull the rifle just a smidge tighter to the shoulder. May help. You're a bigger guy like me. That really helped my off hand shooting. But at my age, I carry me a shooting stick now.
Actually with the swamped barrel your hand is almost back to the trigger guard where it balances. I did do a little better the second time I tried. But I found the trick was ... pull up, on target, FIRE! And it seemed to do better that way.