I still feel that the TAS catwalk scene is inside one of the nacelles, or as designated in the TAS episode, the antimatter nacelle. I estimate that the "set" shown is 40 feet in diameter, and if you add another 10 feet around it for the connected machinery that use the feed from the plasma tubes, you get about 60 feet in diameter. The nacelle is about 60 feet in diameter on a 947 foot ship, so it matches. Gouging out a 60 foot diameter tube room about 160 feet or more long in the secondary hull seems implausible on the 947 foot ship or even in Drexler's huge ship. And what systems are the eight sets of plasma tubes connected to? My guess are the warp field generators (a.k.a. warp coils). It goes along with the
Catwalk episode in ENT and the nacelle scene from TNG; a nacelle trilogy, so to speak. YMMV.