A new facility at Rouses Point would mean having to get off the train. Horrors!
There are a few ways in which C&I is handled on trans-border trains that operate on a route involving travel for many hours in each country in the world:
1. Sealed trains with C&I at point of origin or/and destination. (e.g Kolkata to Dhaka service between India and Bangladesh, C&I at Kolkata International and Dhaka Cantonment stations, Cascades between Vancouver BC and Seattle WA, inspection at Vancouver BC).
2. C&I at the border - two subcases ,
2a Inspection off train (e.g. Maple Leaf between US and Canada, border between Malaysia and Thailand at Padang Besar)
2b Inspection on board while the train is stopped at a station (e.g. when it operated Finland - Russia service with inspection at Vanaikkala and Vyborg)
3. On board inspection while train is in motion (e.g. before Switzerland joined Schengen, inspection between Italy and Switzerland, or France and Switzerland on non stop services)
4. No inspection (The Schengen border situation - hell might freeze over before US and Canadian exceptionalism can deal with that.)
Each of those requires cooperation of the C&I Authorities.
3 requires the most participation from C&I. 1 & 2a require significant infrastructure at the inspection points. Unfortunately 3 appears to be impossible given the bureaucratic attitudes prevalent in both the US and Canada.
1 is difficult to do in a situation where the owners of the terminal and their funders are recalcitrant. (Case of Montreal) Where this can be managed (e.g. Vancouver Pacific Central Station) it tends to work well.
Which leaves only 2a or 2b if you want to run the train at all. Of course 2b is the least expensive and that is why after all the posturing is done, that is what happens when you want to run the train at all. US/Canada seem to prefer 2a, but reluctantly live with 2b i the absence of adequate infrastructure.
Of course there is choice 5 which is discontinue the train and let everyone drive, bus or fly.
For Adirondack we are currently at 2b, with a plan/apparent fantasy of going to 1.