In that case just work with proxy files and only reconnect to the full ProRes files at the end. But again very few clients honestly need 1080p for now. The average viewer can't tell a difference between 720p and 1080p on plasma and LCD TVs. Only the creators of the content can. Stuff going to a big screen are a fraction of a single percent of everything shot real world.
You're correct. In the technical sheets I had, so far, not one time clients have asked for 1080. I've worked one with proxy but didn't like very much. If you're in a plane with little computer power it's very usefull though.