Without the ts parameters of the sub, it would be impossible to make an accurate recommendation, and could be more accurate if they were measured after breakin, but regarding the back being too close, usually I like to keep it at leasy half the diameter of the driver away from the backplate if vented pole piece is used, and for non vented coil cooling systems, the inch away is fine. This is for sealed enclosures. Now, for ported, since you mentioned you may want to switch in the future (and if you do, give me a hollar //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif) then you want to make sure any wall is at least the port width away from the driver and port if possible and have the driver and port themselves at least port width away if possible. So, for a 12 with a round port of 6inches, for example, have the port and sub at least 6 inches apart, and the wall perpendicular to the ports input at least 6 inches away from the inner port opening, and for a slot port, the same applies to the sub an perpendicular wall to the input of the port so the wall can act as part of the port (look at the jlaudio website for an example of what I mean). Hope that helps a little. And someone please correct me if I am wrong.( I typed this very quick,lol)