Sounds like you must be in constant communications with you boss...not my idea of a vacation, but if you do, you might consider renting one of these...Finally using a ticket I bought in February 2000 and will leave Vancouver on Friday and arrive in Toronto on Tuesday.
I told my boss that the wifi and cellular service on that train is spotty and he just wants to know the black holes of coverage. I sent him the timetable and said I expect that I can look at memos at stations along the route but I expect limited coverage for the most part.
I am hoping other members can give me an idea of where service is available.
https://www.vzwsatellite.com/products/rental/iridium9555