I'd go with Canaria and FP9 (or FPXV, right next to each other) being the dropoff points, with all other Zoner stations selling them for a price based on distance to those two dropoffs. Best route in this commodity chain should be Erie to Canaria, as Zoners will want to be leaving Erie for Canaria, due to Liberty's annexation of it.
I just think having two dropoff points would be better than just one, and it'd allow people to have a varied trade route, instead of everyone going to the same place, some can go to GC and then take one of those export routes, or to FP9/FPXV and take one of those export routes, depending on which they prefer or is better in-RP.