I can see that being an issue if the trackbar bracket is offset to the inside of the framerail like with the stock TB bracket, but is clearance still an issue when the TB bracket is moved towards the springbucket centered UNDER the framerail? Not in front of a Jeep which is why Im asking.
the clearance issues not only arise with the diff but the tie-rod. the stock single shear mounting face will actually pass between the diff housing and the tie-rod at full bump.
unless you're a wizard with fabrication, there isn't enough room to slide a bolt long enough to fit a 2.5" JJ in between the diff and tie-rod...so something either hits the diff or the tie-rod, unless you're running enough lift to need enough bumpstop to keep them far enough part.
that's why you'll see fab guys using heims or a 2" JJ max on the frame end. Add up the clearances needed for double shear...you need ~2" for width of joint (or whatever), 2 x 1/4" for the mount and about 1/2-3/4" for bolt & nut head on each end. That means you'll need around a 4"-4.5" long bolt.
Assuming you can thread a needle with the fabbed mount location, and you never have to adjust axle position, you end up needing a minimum of ~4" of clearance between the tie-rod and the diff housing below the frame. Call it 5" to be realistic. It's not impossible to make it work, plenty have done it, but you gotta be a wizard with fab...like the mrblaine & mudb8 guys.
Now, go measure the clearance between your tie-rod and the diff housing and you'll see why the factory and most manufacturers stick with the single shear setup. The factory position of the single shear mount can't really move too much unless you're changing something else...like tie-rod, knuckles, axle position or something....but hey, maybe a 1/2" or something changes things just enough. It's a tight freakin' squeeze in there at full bump. You'll see people also go the other direction...a flat pitman arm and a double shear mount that's really close to the frame. Either way, I say if you're hacking it off to move it...go double shear.