We are finishing out a basement below a double wide that has a roughed-in bath (not our rough-in). There was no allowance for venting any of the bath fixtures, wasn't even a trap run under tub drain rough-in. Is there an AAV available that would vent the sewage pump? Would have to do major destruction upstairs to make access for roof venting. Dug out enough sand to get the tub trap in but am at at a stand-still till venting issue is fixed. Help! Tks, justin