What we have done (much like many of you) is to assign gaps to our defenders (ex. "You have the first threat in the A-gap; you have the first threat in the B-gap; etc.) versus an option attack rather than assigning specific players to segments of the option (ex. the DTs are responsible for the dive; the DE has the QB; etc.). This certainly helps us when we blitz.
As for the midline, we like to attack our 3-techs upfield (penetrate two steps and then sit down looking inside) after getting into a collision with the OG. We find this forces the give as the DT came upfield (the QB will read this and hand the ball off) and severely limits the QB keep action (our biggest concern). Secondly, the ILB to the playside attacks the A-gap aggressively looking for the FB. The backside ILB attacks the backside A-gap and looks for the QB counter. The backside DT plays just as the front side DT as he gets upfield after his collision with the OG.
When we run into significant problems from our base look, our DTs do not get far enough upfield (occasionally too far which allows the QB to cut underneath them but that does not happen often) or our DTs will think about coming inside to tackle the FB. If the DT does not get far enough upfield, we have found the QB's running alley on the midline is huge. That same happens when the DT comes down inside to take the FB on our base look.
We are aware that what we are doing is what the defense wants to see but we will change up our looks (alignments and stunts/blitzes) to give the offense difficulty. The midline is a great play for many teams and it has hurt us. However, we have slowed some teams down - maybe they just got tired of running the same play against us.