I'm trying to figure out how to vent my basement bath and shower drains. In WA state code says you can't roll a vent more than 45 degrees until 6 inches above the flood line of the highest fixture? If I have a drain in the basement along an outside wall that I'm running straight down the middle of the bathroom (so there is no access to a wall to run a vent in any other place in the required distance) and I'm trying to vent along the wall back around the room to the vent, what kind of fittings would I use? Without running the line a few feet close to horizontal I'm not sure how it is physically possible. This is a mock up (a poor one), the wall the line crosses over is too far to meet code so I have to vent out the back. The drain for the bath is going to be a few feet from the wall at the bottom and the other drain is going to be a few feet from the wall on the left.
Thanks in advance for any advice (or even better a picture).