Rick,
I am in the process of trying to figure out how to get a Y into the two hoses that go to my dash mounted vents. The air conditioner needs 4 - 2" vents and I just have 2. I may see if there is room to just take the hose off the back and put in a Y and then another short hose to the vent and let the Y blow down toward my feet. I am getting to old and fat to do much under dash work any more.
Ron