After posting earlier I went back to my pictures and maps, and upon review, it looks like the rebuilding effort of the Naco connection would be easier due to less length and congestion on both sides of the border (the north side being an UP issue, the south side being Mexico's issue). The connection at Douglas/Aqua Prieta has more space on the Mexico side for a yard (including some old boxcars left in place that are now 'homes') - but has more building on the US side of the RoW. The former Douglas station is now restored as a police station, and the old freight house has been a topic of restoration locally for years.

A few years ago (with permission) I traversed most of the trackless RoW now reowned by a class one, finding some neat old broken SP china that had been tossed from the trains, along with foundations and related remains. Lots of wood still around in the dry desert areas . . .