RE: Hunting Northwest Montana
What part of NW Montana? It doesn't matter because you'll want to hunt the does. Camp out on the does and look for bucks cruising to breed does. Decide before hand what size buck you want and don't shoot anything that doesn't meet your requirements. Rattling can work OK in Montana but mostly to bring in something that you've already seen. 8 days sounds like a lot but it's not if you are planning on getting quality representations of both species. You could treat it like 2 four day hunts and focus on deer the first four and rely on scouting reports from other folks in camp when it comes time to hunt elk for four days.
Are you hunting with an outfitter?
Good luck and have fun!