Have discussed this before, but the problem I have is with the ADD OCC that I purchased, it has one inlet, naturally from the PCV valve and two exists, one into the intake manifold where the PCV hose currently exits, then the second is the one I don't feel is proper. That second exit goes to the air intake tube where the OEM air is drawn from, so this means the OEM intake tube is removed and the tube from the OCC is then installed. Now this also means there is no fresh air getting to the engine through the valve cover entry, so their idea is to add an open air filter clamped onto the valve cover, which is illegal and not certain as to how great the filtation might be and/or how often it is to be cleaned, or add a "T" in the line from the OCC to air intake tube. I would go this route, but I don't have the warm and fuzzy feeling that 100% clean, non heated air would be drawn into the engine as it now does with the fresh air entering the engine after it is pulled into the OEM air intake system, then through the air filter, then drawn into the engine.
Maybe I'm being to critical.
As far as the drain hose plug, I purchased a think vacuum hose cap that would be tightly placed over the open end of the hose. There is no pressure in that hose and as the cap is extremely tight as it needs to be turned on, there should be no problem.