another internet and cell phone question

You don't say where you are going this winter. If it isn't in a 4G service area (i.e. a larger city), then I would abandon the idea of downloading even one movie a week. You can still sign up with Netflix to receive DVD's in the mail sent to your campground which in my personal opinion would be better. It would give you more options of movies and no stress of worrying if you are going to exceed your data plan limits. I have found that downloading a one hour TV program (which is really about 40 minutes of viewing without commercials) is about one GIG of data usage.