I'm going to be putting a tonneau cover on my 2500 in the near future. It will probably be a RetraxPro MX, the kind that rolls into a canister at the front of the bed. That canister has drain tubes at each end by the front corners of the truck bed, and the directions show running the tube through existing drain holes. I have a spray-in liner and there are two openings with plugs that could be used but they are both covered with the liner material. Plug #1 feels like soft rubber when I push on it, and #2 feels like hard plastic. Any suggestions as to which one would be better to use? #2 would probably need me to drill a hole for the drain tube, #1 seems like I might just be able to pop it out.