Help with basement slab plumbing for ejector pump

[sleepy hollow]

I am installing a full bath in the basement below the waste stack lines. My house is on a septic field.

I am planning to break up the foundation this weekend to trench for the waste lines. How do I vent the toilet and bath without violating the "no flat venting" code?

Simple diagram:

foundation wall
------------------------
-.pit...lav...........tub-
-.......................tub-
-.......................tub-
-.toilet...............tub-
------------door-------
interior wall

I was planning to run a drain from toilet to pit, and tie in the tub drain to this drain line before entering the pit.

For the toilet, the vent needs to be downstream of the flange, I believe. How do I do that if I am running a drain north from toilet to the pit under slab? Do I need to run it west first under the wall to allow for vent takeoff? What are the "nomal" approaches for this layout?

Help with a strategy would be most appreciated. (I am running a 2" vent to the roof from here to vent all of these fixtures.)

Thanks