My understanding is that the road into Devil's Gate station is still a public road, being the former US Highway right of way. Had it been previously deeded to CHS long ago, then there may have been a case to argue that it was a private not public road.
I heard that Pueblo fell under FRA jusrisdition under the 30 foot rule, perhaps someone familiar with their operation can confirm that.
What is and what isn't insular is really up to the mood of the FRA. USG's Plaster City operation has always crossed the highway (US 80 until I-8 was built), but to the best of my knowledge they are still considered insular. The only reason they now cross the road (besides to get to the other side) is to access the shop. The standard gauge switching operation I managed there was insular, even though we leased the track and UPRR interchanged on our side of the derail. Now that CCZRY uses that track also, I hear that the FRA may no longer consider them insular.
What rules are enforced seems to vary by inspector and for each operation for the non-common carriers. They seem to pay particular interest to the steam locos, but tend to ignore any diesels. Working for a common carrier is a lot easier in the sense that you know all the rules apply, but you still must deal with the individual inspector's interpertations. In Oregon, we also have ODOT rail inspectors who also have FRA authority (this is each state's option). So you can have two inspectors for each discipline.