Bingo, you just described the wiring plan I had in mind. The mystery for me was what went on inside the TIU as far as the grounds. Now I can ignore that by connecting to the output. My old layout only used one TIU output and was limited to one DCS loop. This new layout will have DCS on all tracks, assuming DCS survives the next several years. Oh well, there is always LC 2.o +.
PS- time to buy your season tickets!