I've got 4" to the inner C weld and 4 1/4" to the inner C (weld is 1/4" thick.
My Ballistic fab brackets are 3" from outside edge to outside edge wide.
Also to consider, I angled my brackets so the control arms would angle in as they get closer to the frame. I think this is the propper way to mount the brackets. I've seen people mount axle brackets perpendicular to the axle but to me that puts too much side load stress on them.
You can kind of see the angle and where I mounted them here.
As far as rubbing goes, I have slight rubbing at full lock on the lower arms but I am going to install steering stops soon to prevent that.
Lower control arms - 30" bolt eye to bolt eye
Upper control arms - 15.5" bolt eye to bolt eye