FYI, you don't actually have to get 125 yards in the solo challenge to complete.
Per this thread, I was doing Russell Wilson (Dec. 2013) for 93 yard passing TDs and it was counting. Then I was doing Campaign Week 3 - Shaun Alexander for rushing yards and it was also counting.
Superstars: Russell Wilson: October 6th, 2014 (2nd to the bottom)
Start on the 20: 1 star difficulty
Rush for 80 yards
Onside kick. You don't want to recover it, just hit A, the other team gets it at the 38-42
Run your best QB sack play. As you know, most user sacks on rookie will be a fumble.
If you recover the ball on the 45 or beyond, just run another play to score your 2nd TD and end the challenge.
If everything goes to plan, you'll get 125+ Rushing yards. 125+ All-Purpose yards. 1, win a game with 125+ yards, a sack, a fumble, and 1, win a game with at least 1 sack.
Obviously you can do it with passing too if you want but it's probably better to pair that with the 10 pass attempts objective. For that, any solo where you have to go 75 or so yards and score a TD to win the challenge is best for that. I use The Campaign, Week 1, Baiting for that. Just run a mesh play and hurry up and you can get the 10 pass attempts (10th being a TD) right before the end of the 1st quarter most of the time. Very efficient.