-Slab-on-grade floor
-toilet backs up to an exterior wall

My vent stack/end-of-line clean-out will come up through the footing/slab. In a typical above-grade install, the closet bend would point back to the wall and T into the stack, like this-

But how do I accomdate the requirement for a 2"-oversize sleeve in the footing penetration, if I've got a fitting buried in the footing? Is this a case where a horizontal vent is permitted due to structural/grade restrictions? like this-