To Darth,
I know in the description it says you probably won't work on this any more, but, is there any chance you could add a new end part that works simmilarly to the airtight hangar door in the vanilla game. What I mean by this is that it would look the same as the current piece that works as a merge block, but be a little thicker prehaps. Then you could attach it to the end of the "tunnel" section and then extend it. It would be useful on a ship which has the docking ring at the front and a thick engine nacel at the back, and instead of having to build massive long tunnel thing, they could just place one of these blocks on the end of the tunnel section.
(side note; I'm not a modder and so have no idea if this is actually possible or not)
-Scincerely, Spenno. =)