I would try to do more research on the legal status of the rail trails. Here's why.
There is (or was) an organization called "Rails to Trails" that a few years ago was instrumental in setting up a lot of these hiking/biking trails on old RR rights-of-way. They operated under a federal law which, if I recall correctly, was called something like the National Railbanking Act. The premise of the law was to preserve abandoned RR rights-of-way so that, in the future, if this country ever regained its sanity and started shipping by train again instead of trying to build still more highways, the rights-of-way would be there, ready and waiting.
I thought this was a great idea, and for a couple of years I contributed to this group. Then I read something in one of their mailings that caused me to wonder. So I called, and I asked what would happen if in an unspecified number of years, a railroad decided it wanted to start up again and actually use one of these "railbanked" R-O-Ws for a railroad. The response? "Oh, we would oppose that very strongly."
The open question is, if the trail to which you refer was created using the federal railbanking law, that law may provide some provisions as to whether or not the trail is, in fact, private property, or if it in fact a permanent easement ACROSS private property, open to the public. If the latter, it is likely that state law applies and the landowner can't prevent open carry if legal under state law.
