After two months of false starts, I'm starting to make progress!
Got another 9 feet of track installed yesterday! Now if I can tackle getting the bridge piers cut I can envision 'closing the loop' on the outer track. (Then comes the fun of wiring and soldering!)
Also started laying the roadbed for the inner loop. The western half will be easy, but I need to plan out the eastern half to ensure I get the track in the right place and get all the sidings mapped out. On the plus side - this is the fun part!