Actually, "level" (meaning straight out from the axle) is really just a rule of thumb representing the configuration that is about as good as you’re likely to get it. The real deal is that when viewed from the side, you draw a line from the contact patch of the rear tire through the pivot point at the forward end of the bar. You want to keep this line as "level" as possible. Obviously there are ground clearance issues that are in opposition to this goal, so you just get as "flat as you can” without giving up ground clearance. Since you pretty much stuck with the axle tubes, putting the forward point of the bar just a bit above that level is the common solution. So, a longer bar will “flatten” the line, given all other things remain the same. And mounting the forward end lower will also reduce the "anti-squat" characteristics by “flattening” the line. But the axle side mount has no bearing at all on the anti-squat... You could mount it on a tower above the top of the roll cages, and baring mechanical interference or failure, it would make no difference.