Rick nailed it guys, the FRA won't allow it, the way you are dreaming about doing it.
The 1225 guys run their program within yard limits and with the "engineer for an hour" issued a student license. This requires a physical exam from your doctor and several hours of classroom time. The FRA then permits the "student" to operate under the supervision of a licensed engineer, within yard limits only. For your $350 you get the class and an hour at the throttle. They still sell out all available slots.
Even a licensed engineer would think twice about running on the C&TS without lots of left side time for learning the line. Figure two years as a fireman at a minimum, before moving over to the right side. It's not so much the uphill trip, as the downhill trip that takes the time learning.
Just because the Friends is a volunteer group, don't expect them to act like railfans when it comes to running their railroad. Management has just reiterated the "no cab rides, period" policy. Safety is numero uno!