With great pleasure, I am happy to say that the mainline track loop was connected today. The section along the bottom of the track plan drawing along the west wall was difficult, as expected. A 3 foot section of track actually was torn out and re-laid in this area, but is now complete and I can run a train around the loop of mainline. This effort took longer than planned, but I am happy with the result and the trains run pretty smoothly.
Although none of the branches or yards are completed except the small north wall staging yard, at least I can enjoy building a train and sending it around to let off a little steam, as it were. I think I can now work at a more reasonable pace.