Here's what i have, and what i want to do when i remodel the bathroom. I also want to hide all the pipes against the wall or between the joist so as to be able to finish the basment easily. Right now they are all sticking out in the open.

I live in PA and think i'm under the 2003 IPC.

Right now, the toilet sits on top of the 3" stack, and is not vented. I'm not sure how i could fit the two 90 bends in there later, still tucked inbetween the two joists, and get a vent there too. Anyways, the pics:

Now here's what i want to do:

This is the elbow i was talking about using there with the side inlet:

Or is there a better solution that i'm missing? I want to be able to keep the plumbing in between the joists so i can drywall the ceiling below it. Thanks in advance.