Aw man, hate to see you having a problem with the lower back. I have been there many times and I'm there now. Squats yesterday made it feel better tho, so I am glad to hear the fronts felt good.
Is there any plans to get it checked by either a Doc or a physiotherapist?
Indeed, front squats and Oly lifts are definitely the best for Abs.
At any rate, I hope you are back to pulling shortly.
My Favorite Part Of Lifting Is Having The Opportunity
Squat 403 lbs
Bench: 253 lbs
Deadlift: 463 lbs
Total: 1119 lbs