In working out my DWV system, I need to add any fittings I will need for a future basement bathroom. I had a plumber do the under-slab DWV, and rough-out stubs for a full bath. What I don't see is how/where to connect the lav. In the picture, starting from the left is the tub (with the yellow bucket on it), the toilet, a 2" vent (for the entire bathroom, I assume), the main stack going up to the main floor, and then out through the roof for venting, and a radon mitigation vent (not part of the system, but in the picture). I don't think I can connect the lav drain directly to the main stack, can I? Can I connect to the 2" vent? Then it becomes a wet vent. Or should I come off the main stack with a combi, which would have a vertical vent which can then tie to the 2" vent @ 42" above the floor, and long sweep ell out to the lav drain? All of that would have to go to the left, since the radon tube is in the way on the right. I do have enough room (barely) if I go left to house the lav in a vanity and still have over 15" to the centerline of the toilet. Thanks!