I like it.
I had the same thought but then the exhaust would just run by the sliders and get totally smashed to bitsIt would be so much easier if you could just run the exhaust outside the frame easily and not have it in the way of anything inside or outside the frame rails. So you could just put it somewhere once and leave it.
I can get a piece of 2.5 round between the t-case and frame, so it'll go after 1000 wrong cuts and some swearing.You'll be able to get it through, and this will probably be the last time you do it, because it'll be as close as possible to the frame. Don't forget you have ovalized tube options if need be. Also you can then reflective heat shield the areas near here.
With that said, I was able to get 2.5 through with my tcase and crossmembers above the bottom of the frame rail, so I know you'll be able to get it. I had to hammer one small spot to get it from hitting.